Four remaining Republican presidential candidates duked it out at the Fox Theatre in Detroit Thursday night, two days after Super Tuesday greatly widened the delegate count between the contenders.

Before Fox host Bret Baier, one of the moderators, introduced the candidates, Bill O'Reilly offered his thoughts on the spat between former Republican nominee Mitt Romney and current frontrunner Donald Trump. O'Reilly acknowledged the Romney's speech and Trump's response, but said that he won't make any judgments about who is in the right.

Baier emphasized that 59 Republican delegates are at stake in Michigan on Tuesday, when four states will have their nominating contests.

The candidates were introduced in the order of their relative standing in the race. Trump was introduced first, followed by Texas Sen. Ted Cruz, Florida Sen. Marco Rubio, and Ohio Gov. John Kasich.

Moderator Chris Wallace directed the first question of the evening at Trump, asking him to respond to Romney's scathing criticism of his policy positions and personal attributes including "bullying, greed, misogyny, and absurd third-rate theatrics."

Trump responded by calling Romney's candidacy a "miserable failure." With regard to policy, he said that he believes in free trade, but better deals are needed because "Japan, Mexico, China are 'crushing' us."

Wallace then asked Trump about his views on the KKK and white supremacism. Trump was adamantly said, signature finger-wag included, that he "totally disavows" the KKK and David Duke, though he did say that others needed to be specific about "which groups" were bad. He referred to Twitter for proof that he immediately denounced the KKK again after Romney's diatribe.

The next question was to Rubio's about his apparent reversal on his initial position to not launch personal attacks on his opponents. The senator defended himself, saying that Trump deserves to be attacked for the derisive way he has treated his fellow candidates. Rubio also faulted the media for giving Trump's personal attacks an "incredible amount of coverage."

Trump responded with a backhanded compliment and a glib remark that "no one has ever attacked [his] hands before."

Moderator Megyn Kelly jumped in with her first question of the evening directed at Cruz, asking him whether his failures with his supposed core voter groups, such as Evangelicals and conservatives, show that Republican voters prefer Trump's populist message over his brand of "true conservatism."

Cruz said that struggling American people are interested in "solutions, not slogans." He re-iterated his core campaign promises, including reining in regulators, "repealing every word of Obamacare," abolishing the IRS and putting a flat tax into place. He claims his is the only campaign that will beat Trump.

Trump emphasized the number of votes that he beat both Cruz and Rubio by on Super Tuesday. Rubio countered that when looking at the numbers, two-thirds of people who have voted in the primaries have voted against Trump. He also emphasized Trump's defense of Planned Parenthood as proof that he is not a true conservative.

Kasich was asked about Romney's proposed plan to create a contested convention. He responded that he could get "crossover votes" because he is the "adult on the stage," and expressed hope that voters in the north and midwest will see his experience in Washington as Chairman of the House Budget Committee as proof that he can create economic and wage growth.

Unemployment

Rubio redirected a question about how many jobs he has created to a criticism of Trump.

"Trump has spent a career convincing people that he's something he's not in exchange for their money, and now he's trying to do the same in exchange for their country." He also attacked Trump's inheritance and the fact that Trump-branded clothing is made in China.

After calling Rubio a "little guy who lies", Trump launched into a highly technical justification for outsourcing, which included currency devaluations.

Rubio and Trump then started unintelligibly arguing about whose policies will better benefit the economy, with Trump repeatedly calling Rubio "little Marco."

When asked about the discrepancy in national savings in his tax plan, Trump said that he will eradicate education and environmental regulations at the federal level, citing excess "waste, fraud, [and] abuse."

Fox refuted his claims with a series of graphics showing that curbing regulatory agencies and Medicaid drug costs would still leave a deficit exceeding $300 billion. Trump had few words.

Cruz was then asked about the affects that abolishing the IRS will have on tax collection. He said that only an office in the Department of the Treasury will be necessary under his plan, because every American will be able to fill out their taxes on a postcard. He subsequently attacked Trump's apparent complicity with "the corruption in Washington" for over 40 years, citing his repeated support of "liberal Democrats."

Trump defended his past actions by saying that he was not a politician before, but his record of supporting both sides shows that he can "get along with everyone."

Regarding his past support for a higher minimum wage, Kasich said that states can vote to increase minimum wage but made little mention of whether the federal minimum wage should also be raised. He again referenced his role as chief architect of the balanced federal budget during the Clinton Administration and his record on job creation.

Immigration

The debate returned with a question for Cruz. Sen. Jeff Sessions (R-Alabama), who worked with Cruz to fight illegal immigration and amnesty, had paradoxically endorsed Trump. Cruz was asked to account for this inconsistency, but he punted the question and brought up the fact that Trump donated to current Democratic frontrunner Hillary Clinton's 2008 campaign multiple times.

Kelly asked the next question, intended for Trump. They bantered before Kelly was able to get an entire sentence out. Trump facetiously complimented Kelly, saying that she was "looking well."

This hard-hitting question referred to Trump's self-professed "flexibility" on immigration policy, specifically with regard to deportation of people who are in the country illegally. Kelly cited an off-the-record interview with the New York Times, which was recorded.

Trump responded by reiterating the need for flexibility and negotiation to "get things done." When pressed, however, he said that he's "not very flexible" on this specific issue. He also reminded the audience that he is the one who "wants the wall" on the U.S.-Mexico border, one he will get Mexico to pay for.

Rubio was questioned about his role in the "Gang of Eight," which wrote the 2013 comprehensive immigration reform bill that among other policies, supported a path to citizenship for people in the country illegally. The moderator emphasized that Rubio was also in favor of in-state college tuition for such people, implying that his record on immigration may not be so hard-line. Amid boos from spectators, the senator said that Trump should authorize the release of the recordings of his New York Times interview, but affirmed that he will make sure immigration policies take precedence if he is elected president. In an apparent jab at President Obama, he wrapped up by saying that he won't be issuing an executive order to resolve this issue.

Trump responded that he will not release the tape because he "has too much respect for journalistic process." When asked about flip-flopping on the issue of H1B visas for highly skilled workers, he affirmed the need for these migrants, saying that he was "softening" from a hard-line position on foreign workers while maintaining a stance against people in the country illegally that was as strong as his peers'.

Cruz, who has similarly reversed his position on H1B visas, pointed to rampant abuse of the program by U.S. companies that allegedly fire domestic workers and "import" foreign ones who they can pay less. He also suggested a full investigation of the entire program. The senator then pointed to one of Trump's hotels in Florida, which he claims has been engaging in this very kind of abuse.

Cruz said this, along with the Times interview, was proof that "Donald doesn't believe what he's saying. For everyone at home who's mad, he's not the guy."

Trump defended the practice, saying that the hotel hired so many foreign workers because "Americans don't want part time jobs."

Rubio joined Cruz in coming down hard on Trump. He said that employers of H1B visa workers do not have to compete in wage market because their employees are "held captive" by the company that sponsored them.

Cruz then again urged Trump to release the interview, so that this issue can be resolved "very quickly." The exchange between the two then devolved, with each calling the other a liar amid other unintelligible yelling.

Terrorism

The moderators returned from the second commercial break with pivotal questions on foreign policy, starting with the Islamic State. Each candidate was asked what he would do to stop the threat as a commander-in-chief.

Rubio kicked off the discussion when he was first asked why he did not support sending ground troops to Libya as he did for Syria and Iraq, when Libya is currently home to the biggest Islamic State threat. He said that the U.S. must deny radical groups operating spaces, so they need to be targeted wherever these spaces may be. He also emphasized that the Islamic State needs to be defeated on the ground by forces made up primarily of Sunni Arabs, with support from American special operators and airstrikes.

After a long period of silence, Kasich finally rejoined the debate by emphasizing his experience in military policy, namely the 18 years he spent in the House Armed Services Committee and his role in assisting Secretary of Defense Rumsfeld following 9/11. He then launched into a scathing criticism of Clinton's plan to depose Qaddafi while she was secretary of state, for which he claimed there was "no reason," and which left a fertile ground for the Islamic State. His plan to defeat the Islamic State would include the U.S.' "Muslim Arab friends," a broad coalition similar to the kind that helped defeat Saddam Hussein. The function of military policy is to be "cold, calm, deliberate, take care of the job and come home," he concluded.

Trump was then called upon to account for his support of extensive use of torture, which many prominent figures have deemed "inexcusable." His call to target terrorist families and use interrogation techniques more extreme than waterboarding has many in government worried that the military will refuse to follow him as commander-in-chief because they have been trained to refuse such orders.

His response was simple: "They won't refuse."

"The Middle East is chopping off heads of Christians and drowning people in steel cages," he said. The audience cheered loudly when he said that he will "go stronger than waterboarding."

"Yelling and cursing at people doesn't make you a tough guy," Cruz said. He declared that he would rebuild the military, making it so strong and feared that anyone who attacks the U.S. will be "signing their death warrant."

Cruz was then pressed about his tardiness to condemn NSA whistleblower Edward Snowden as a traitor. He fell back on his legal career, saying that he waited for more evidence to emerge before he formed a conclusive opinion about whether Snowden should be prosecuted. He condemned Snowden for undermining the ability to defend the country, and for making it easier for terrorists to evade detection.

Trump went a step further by calling Snowden a spy for China and Russia. When asked about who he thinks are the "best" to advise him on policy matters he is unfamiliar with, the real estate mogul listed Council on Foreign Relations President Richard Haass, Gen. Kline and Col. Jacobs.

Kasich referenced his win in Foreign Policy magazine's contest on the best leader to conduct U.S. foreign policy. He reminded the audience of his extensive experience in Congress and his record of working with Ronald Reagan.

The moderators then showed video clips that seemingly defied Trump's assertion that people like him because he "tells it like it is." The clips juxtaposed Trump claiming polar opposite positions on key issues, such as the war in Afghanistan, accepting Syrian refugees and whether Bush lied to gain support for the Iraq War. Trump said that he was "always against going into Iraq, but when pressed on exactly how many times he's flip-flopped, he self-assuredly said that he has "never seen a successful person who doesn't have a certain degree of flexibility."

Kasich attacked Trump on this very point, remarking that Americans are so upset because politicians have made too many promises that they do not deliver. He pointed to his successful promises, namely balancing the budget while cutting taxes.

"Outsiders can't bring change," he asserted. This, he said, is due to their lack of understanding of compromise or policy, which will only further frustrate the public. He said voters should pick someone who has a record of achievement – him.

"There is a difference between flexibility and telling people whatever they need to hear to get them to do what he wants them to do," Rubio said to cheers from the audience. The senator pointed to Trump's failed private university venture, Trump University, as an example of when Trump failed to deliver on his promise that he would "hire the best people."

The pair, again, started to argue incoherently.

Kelly took this opportunity to dig deep into Trump's business record. She listed off the myriad of failures, consequences of which continue to this very day. She specifically said that Trump University is the subject of a class action lawsuit with over 5,000 plaintiffs who believe they were cheated. She also said that Trump's own rating with the Better Business Bureau is a D-.

Trump, visibly agitated, insisted that his BBB rating is actually an A, and he snapped back with the line that he does not comment on pending litigation.

Rubio took this opportunity to throw another punch: "He's trying to do to American voters what he did to people who signed up for Trump U."

Trump brought up some of Rubio's harsh realities. The businessman attacked his absenteeism in the Senate, calling him the "true con artist" for depriving his constituents of representation.

"He couldn't get elected dogcatcher," Trump said.

Cruz took his moment to sum up the evening.

"Is this the debate you want playing out in the general election?" he asked, saying that if Trump is elected president, he will be involved in a fraud lawsuit for his first year.

Trump looked visibly uncomfortable. Cruz then urged voters to stand with the coalition of people who believe in the Constitution – implying anyone but Trump.

The mogul then invoked his high polling numbers as proof that he was the best candidate, despite all of the criticism. He and Cruz proceeded to argue about how polls answered the question. Trump seemingly came out of this spat on top because reiterated that he won more Super Tuesday states than anyone else on the stage.

Kasich took the high road, redirecting the conversation to the needs of the American people. "People want to believe they have the power to fix things where they live," he noted. They yearn for someone who will bring America back, at both the leadership and the neighborhood level."

"Let's stop fighting," he concluded.

Social Issues

The debate's final segment began with an uncomfortable question. Why haven't the Republican candidates done more to address the disaster in Flint, Michigan, while both Democratic contenders have both paid personal visits there?

"Flint is a systemic breakdown of government at every level," Rubio began. The audience began cheering when he criticized Democrats for turning the issue into a partisan one, saying that politicizing the issue is unfair. He defined the proper role of the federal government as one that helps local communities respond and ensures that this type of disaster never happens again.

Kasich was asked whether the federal government should bail out Detroit schools the same way it bailed out the auto industry, given that urban blight has essentially paralyzed public education in the city. He said that while all urban schools are in need of overhaul, the responsibility for fixing them rests at state and local levels. He voiced support for expanded vocational training and school choice, which brought cheers from the audience.

"Adults have to fight in our neighborhoods and communities for our children's education," he concluded.

Cruz was then asked about his plans to bring manufacturing back to America. He said that blue-collar workers, such as workers in Detroit, should be trained to do those jobs. After a lengthy praise for the history of Detroit, he condemned "left-wing Democrats that have pursued destructive tax policies and weak crime policies…." He said his "border-adjust plan", the highlights of which include repealing Obamacare and pulling back regulators, will produce the "level playing field" that businesses need to thrive again.

Kasich was asked to clear up his past statements on gay marriage dissenters, in which he seemed to diminish their rights to not participate in facilitating same-sex weddings. After a few stutters, he fell back on his personal record as a man of faith. His recommendation was for everyone to practice common sense, such as respecting each other, being more tolerant, and not going to court over issues like a wedding photographer refusing to work for a same-sex couple. He said he still supports protecting people from being "pressured to participate in something that's against their deeply held religious beliefs."

Cruz expanded on his position on adoption for same-sex couples, insisting that it, like marriage, should be decided at the state level. He called himself a "believer in the Tenth Amendment." He said the Supreme Court decision was decided by "five unelected judges," and that it was, "illegitimate and wrong." He promised to "never compromise away religious liberty," which he counts as a lifelong passion.

Trump had nothing more to add. In his shortest statement yet, he said that he was "shocked" by the decision but would prefer that the question of marriage be left to the states.

The next question, on limiting gun rights, was directed at Rubio. The senator affirmed that he would draw as few limits as possible because life, liberty and happiness cannot be accomplished without safety. He said limiting Second Amendment rights would only prevent law-abiding people from protecting themselves, while doing nothing to deter criminals because they don't care about the law anyway.

Trump reversed his previous position of advocating a ban on assault weapons.

Cruz's simple recommendation was to not restrict Second Amendment rights at all. He cited the apparent failure of the Clinton Administration's wide ban on certain types of firearms to deter crime, and he criticized Trump's inability to properly defend the right to bear arms, citing the businessman's previous donations to leading Democrats such as Nevada Sen. Harry Reid and New York Sen. Chuck Schumer as evidence.

Trump fired back, attacking Cruz for supporting the confirmation of Chief Justice John Roberts, whom Trump claims was the "primary supporter" of Obamacare.

The debate devolved into incoherent yelling one last time, but this spat became particularly uncivilized.

"I know it's hard not to interrupt," Cruz condescended. He told Trump multiple times to "breathe".

Rubio took the opportunity to throw another punch at Trump. "He's very flexible, so you never know," referring to yet another instance of Trump flip-flopping on policy.

The moderators prompted Rubio to say why Trump is not qualified to be president. Rubio said that Trump "has not shown seriousness about foreign policy issues or intellectual curiosity and interest in learning about the issues."

Trump decided to go for the ad hominem attack. "Believe me, Marco is not a leader," he scoffed.

When asked about military leaders saying they would not follow orders to kill civilians or torture, Trump said "They'll do as I tell them," and that he would "prove to be a great leader."

Rubio then brought up Trump's admiration for Russian President Vladimir Putin, attempting to make his point heard above Trump's repeatedly shouting "wrong, wrong, wrong."

"Putin said very nice things about me," Trump said. He voiced a desire for the U.S. to "get along" with Russia.

The moderators interjected with one of the day's breaking news events – that North Korean leader Kim Jong-Un had ordered nuclear weapons to be made ready. When asked how he would respond, Cruz chalked up the standoff today to the Clinton Administration's choice to negotiate a deal with North Korea, which used the money to purchase nuclear weapons.

The moderators then showed a part of a Kasich campaign ad, which included Trump's quotes on Putin as well as a statement that Trump would "make tyranny great again." He earned cheers from the audience when he said that he's "not biting."

Baier moved the debate toward a close when he asked each candidate whether they would honor the pledge they signed to agree to support the Republican Party's nominee, even if that person is Trump, and not pursue an independent run.

Rubio said that he would. "Democrats have two people left: One is a socialist and the other is under FBI investigation…and lied to the families of victims of Benghazi," he said.

Cruz also said he would honor his word. He qualified his statement, however, with a reference to his 17 point win in the Texas primary, which he took as powerful affirmation that the people "who know him best" know that he will fight for his beliefs.

Kasich said outright that he will "be the nominee when all is said and done." He said if it is not him, however, he will support the nominee even though it will be "hard."

Trump was asked if he would support the nominee even if it is not him. He gave a sort of non-answer, saying that he is proud of brining people into the Republican Party.

The candidates were each allotted 30 seconds to give a closing statement.

Kasich promised to go back to Washington, fix all of the federal government's problems and "restore the spirit of America."

Rubio followed his tune, proclaiming that the "21st century can be the greatest era in the history of the United States," but only if we get this election right.

Cruz promised to "have the back" of a litany people who have been "left behind by Obama."

For the final statement of the debate, Trump vowed to bring jobs back to U.S. like no one else can, so that Americans can be "very very proud" of their country.

Reach Opinion Editor Ashley Yang here; follow her on Twitter here.