Trump in the crosshairs at rowdy GOP debate

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Marco RubioMarco RubioCoulter: Trump's 'softening' on immigration remark a panic move Poll: Trump holds narrow lead over Clinton in Florida Clinton enjoying edge over Trump in Silicon Valley MORE and Ted CruzTed CruzThe Trail 2016: Control the Alt-Right Shift Trump: Rick Perry would 'do well' against Cruz Conway, Kelly clash over Trump’s use of personal insults MORE continued their scorched-earth campaigns against Donald TrumpDonald TrumpCoulter: Trump's 'softening' on immigration remark a panic move Clinton on pay-for-play accusations: a lot of smoke and no fire Trump ties campaign to Brexit: Time to 'redeclare' US independence MORE at the Republican debate in Detroit on Thursday. 

The two freshman senators are desperately seeking to hang on against Trump, who is threatening to run away with the nominating contest. 

Both kept the pressure on Trump over his business career, his past support for Democrats, his electability and his position on immigration. 

Trump started off the debate calmly seeking to rise above the fray, but the incessant attacks eventually got under his skin, and he kicked back hard at “Little Marco” and “Lying Ted.” 

In perhaps one of the most shocking moments of an already unpredictable campaign, Trump directly addressed Rubio's previous criticism of his "small hands." 

"He referred to my hands — if they are small, something else must be small,” Trump said. “I guarantee you, there's no problem.” 

The exchange provoked groans from the crowd and hand-wringing among prominent conservatives on social media, who worried that the candidates were debasing themselves to the benefit of Democrats in the fall. 

But the debate only spun out of control from there as the candidates bickered over their polling numbers and shouted about who would do best in a head-to-head match-up against Hillary ClintonHillary Rodham ClintonClinton on pay-for-play accusations: a lot of smoke and no fire Trump ties campaign to Brexit: Time to 'redeclare' US independence Clinton: Trump 'peddling bigotry and prejudice and paranoia' MORE

“Gentleman, gentleman, you’ve got to do better than this,” moderator Chris Wallace muttered at one point. 

Rubio kept up his aggressive attacks against Trump, although he had to defend his increasingly personal barbs against the front-runner.

Rubio argued that Trump has mocked everyone from his rivals to disabled reporters and that the media has only rewarded him with more attention because of it. 

"If there has been any candidate who deserved to be attacked [in this] way, it's Donald Trump for the way he has treated people in the campaign,” Rubio said. 

Trump, meanwhile, addressed the wild events that had transpired earlier in the day, when Mitt Romney gave a major address in which he sought to embarrass and humiliate the front-runner. 

Trump cast Romney aside, calling him a "failed candidate" searching for relevance. 

“He should have beaten President Obama very easily," Trump said. 

He called Romney "an embarrassment to everybody, including the Republican Party," before apparently making a comment about Romney's tanned skin.

"He went away, looks like he went on a vacation the last month,” Trump said.

Cruz also kept the heat on Trump, ticking through all of the times he has donated to Democrats and supported liberal causes. 

In one exchange, Cruz demanded Trump answer to how he could challenge Hillary Clinton on the debate stage when he supported her for president in 2008. Here, he made a direct appeal for Trump’s supporters. 

“To the folks who are supporting Donald right now: You’re angry. You’re angry at Washington, and he uses angry rhetoric,” Cruz said. 

“But for 40 years Donald has been part of the corruption in Washington that you’re angry about, and you’re not going to stop the corruption in Washington by supporting someone who has supported liberal Democrats for four decades.” 

That’s the message Rubio sought to drive home as well. 

“The numbers say that two-thirds of the people who have cast a vote in the Republican primary have voted against you, they do not want you to be our nominee,” Rubio said. “The reason is we’re not going to turn over the conservative movement … to someone whose positions are not conservative.” 

Trump has absorbed those attacks before and they haven’t stuck. 

Still, the front-runner had his hands full with the debate moderators. 

He and Megyn Kelly faced off for the first time since the first GOP debate after months of public feuding. They were cordial to start. 

“Mr. Trump, hello, how are you?,” Kelly asked. 

“Hello Megyn,” Trump responded. “Nice to be with you. You’re looking well.” 

But Kelly had several critical, though civil, exchanges with Trump that could have a lasting impact on the race. 

She pressed Trump repeatedly on the off-the-record exchange he had with The New York Times about immigration. 

“You’re not releasing the audio, which will have some asking whether on immigration you’re just playing to people’s fantasies, which is a tactic you’ve praised in your book '[The] Art of the Deal,'” Kelly said. 

Later, she got Trump to change his position on visas for foreign workers seeking employment in the U.S. 

“Time and time again you’ve told the voters one thing only to reverse your position in a matter of weeks or days,” Kelly said. 

Trump’s rivals may already be cutting campaign ads with his response: 

“You have to have a certain degree of flexibility,” Trump said. 

But Rubio and Cruz didn’t escape unscathed either.

Both were put on the defensive by Fox News’s aggressive panel of moderators. 

Rubio had to answer for the personal attacks he’s levied at Trump, even as he’s claimed to run a campaign focused on the issues. And Chris Wallace at one point asked Rubio point blank: “How many jobs have you created?” 

Cruz had to answer a question about whether his brand of conservatism has “been rejected” in favor of Trump’s populist pitch. Megyn Kelly pointed out that Sen. Jeff SessionsJeff SessionsTrump vows to protect jobs, wages for Hispanic voters The Hill's 12:30 Report Ex-Eric Garner prosecutor calls for Clinton Foundation special prosecutor MORE (R-Ala.), a fierce immigration hawk and frequent touchstone for Cruz, is supporting Trump for president. 

Ohio Gov. John Kasich didn’t get a question for the first 15 minutes of the debate, and when he did, he was forced to defend his position in the race. 

“Voters need to see a path to the nomination if they’re going to support you,” Baier said. 

Kasich vowed that he’d win his home state of Ohio, a critical winner-take-all contest that will vote on March 15. 

The Ohio governor didn’t tangle with his rivals, instead sticking to the positive message that’s gotten him this far. 

“I never get into these fights and people say everywhere I go that it makes me look like the adult on the stage,” Kasich said.