The vicious brawling between GOP heavyweights has reached new heights right before the big debate

The Republican presidential contest has devolved into an all-out brawl ahead of a the Thursday-night debate.

With the first two nominating contests only weeks away, candidates vying for the top slots in Iowa and New Hampshire have begun taking shots at each other on everything from their professional records to their right to even be president in the first place.

Several candidates, notably former Florida Gov. Jeb Bush (R), have become increasingly critical of the resilient Republican front-runner, Donald Trump.

“Do you want a president who disparages women? Muslims of all kinds, people with disabilities, Hispanics — I mean, we’re getting down to about 90% of all people here,” Bush said last Wednesday. “I mean at what point do we say, ‘Enough of this?'”

Former Hewlett-Packard CEO Carly Fiorina also took a swing at Trump last week. The Republican businesswoman compared Trump to reality star Kim Kardashian.

Though both Fiorina and Bush were once the subject of much public scorn from Trump, the real-estate mogul has since turned most of his attention to a surging rival whom he had long declined to go after: Sen. Ted Cruz (R-Texas).

As Cruz snatched the lead in some Iowa polls, Trump called Cruz’s eligibility for president into question almost every day since last week. Cruz was born in Canada to an American mother, and most legal experts consider the senator a “natural-born” citizen under the US Constitution.

However, as Trump repeatedly pointed out on Twitter, the courts have not ruled decisively on the issue:

At rallies and in television interview appearances all last week, Trump suggested that Cruz could get caught up in some sort of prolonged legal entanglement if he were to win the nomination.

“How do you run against the Democrat, whoever it may be, and you have this hanging over your head if they bring a lawsuit?” Trump asked during a said in a CNN interview last Wednesday.

Sen. Rand Paul (R-Kentucky) also piled on, joking that Cruz was certainly eligible to be prime minister of Canada, but refusing to say whether he believed Cruz was eligible to be president. Paul also told CNN that he believed it was hypocritical for conspiracy theorists to question President Barack Obama’s birthplace — as Trump once did — and not raise the same concerns about Cruz.

“There’s been a double standard on the whole birth issue,” Paul told CNN’s Don Lemon.

Though Cruz at first attempted to make light of Trump’s questions, the Texas senator has since become increasingly aggressive in pushing back. In an radio interview on Tuesday, Cruz suggested that Trump was getting worried about his surging campaign. Cruz also attempted to tie Trump’s attacks to Democratic presidential candidate Hillary Clinton.

“She and Donald know each other well,” Cruz said of Clinton. “And I do think it’s interesting that Hillary Clinton’s key supporters are doing everything they can to echo Donald’s attacks on me. We’ve seen in the past couple elections where the Democrats worked very hard to ensure that they face the Republican they most wanted to face in the general election.”

Cruz also took a jab at Trump’s general-election poll numbers against Clinton.

“It may be driven by the fact that the polling right now shows Donald loses to Hillary — and loses by a pretty big margin. But I beat Hillary. And I think that’s got the Hillary folks a little bit concerned. And so they’re doing everything they can to amplify Donald’s attacks,” he said.

A Wednesday CNN segment on the back-and-forth was titled: “TRUMP AND CRUZ LOCKED IN BITTER BROMANCE BREAKUP.”

Vicious attacks have increasingly become a prevalent part of the final sprint before the first two nominating contests.

The 2012 Republican primary saw the highest levels of negative campaigning in recent history. Ads like former Massachusetts Gov. Mitt Romney’s (R) one comparing former Sen. Rick Santorum’s (R-Pennsylvania) governing record to a drowning body hit the airwaves in key primary states and didn’t let up for months.

“I actually don’t think it’s especially brutal,” GOP strategist Liz Mair told Business Insider about the 2016 race. “Go watch debates from 2008 — it was more brutal then, if I recall correctly, with a lot of people going hard against each other in that context where sometimes people want to do more for longer to ‘look nice.'”

Faced with a barrage of attack ads launched by groups supporting Romney in 2012, former Speaker of the House Newt Gingrich had a response that was similar to New Jersey Gov. Chris Christie’s (R) response to attacks from Sen. Marco Rubio’s (R-Florida) allies today.

But the jockeying for support in New Hampshire this time around is also far from cordial, even among the so-called establishment candidates. Recent polls show Rubio and Christie locked in a dead-heat for second place, with Ohio Gov. John Kasich (R) and Bush trailing just a few points behind.

In recent weeks, multiple teams began running negative ads against Christie as the governor fired back.

“This isn’t my first rodeo,” Christie said, “and if Rubio thinks by putting out a couple of negative ads on me that somehow he’s going to intimidate me, it just shows how inexperienced he is, and how unprepared he is to be our candidate against someone like Hillary Clinton.”

Christie also went after Bush, whose campaign and allied super PAC criticised Christie for his New Jersey track record.

“Jeb can say whatever he wants to say, and you can tell him, stop saying I’m a nice guy and he likes me,” Christie said, according to CNN. “I don’t need the fake compliment leading into the criticism.”

At this point, even the smallest details are apparently fair game for criticism.

After a New York Times reporter noticed that Rubio was sporting a seemingly stylish pair of black leather boots, Paul quickly mocked the senator’s “cute” sartorial choices. Soon, a super PAC supporting Bush released a bizarre web ad about the boots.

“Some of the attacks between the candidates are weird, and reinforce the notion that they’re not necessarily getting tough — and not just with Trump,” Mair said. “Making an issue of Marco Rubio’s footwear strikes me as particularly odd.”

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