IE 11 is not supported. For an optimal experience visit our site on another browser.

The flip side of the pledge: Are Trump's rivals willing to support him?

The RNC's pledge –- designed to box in Trump -– also begs the question: Is the GOP really ready to support Trump if he wins the nomination?

The GOP establishment let out a sigh of relief Thursday when Republican presidential front-runner Donald Trump signed a pledge ruling out a third party run, staving off fears that he’d undercut the eventual Republican nominee by running on another ticket.

But the pledge – designed to box in Trump – also begs the question: Is the GOP really ready to support Trump if he wins the nomination?

RELATED: Donald Trump signs RNC 'pledge' to support GOP

The Republican National Committee began circulating the pledge this week, reaching out to presidential campaigns and requesting them to sign on. It asks candidates to "affirm that if I do not win the 2016 Republican nomination for President of the United States I will endorse the 2016 Republican presidential nominee regardless of who it is." 

If they sign and Trump eventually wins the nomination, the rest of the party would have to throw its support behind a candidate who has disparaged women, criticized undocumented immigrants and said Sen. John McCain was not a "war hero" in just a few months -- undercutting their efforts to expand the party base -- and who decades ago was publicly a Democrat. The pledge, however, is not legally binding, meaning a candidate could renege on their word.

Trump “would be a disaster for the country and a disaster for our party,” Republican White House hopeful and Sen. Rand Paul said Thursday on Fox News, but he too also said he would sign the pledge not to run as an independent. Paul added: "Ross Perot gave us Bill Clinton, and Donald Trump could give us Hillary Clinton.”

“Look, if Trump’s the nominee, all bets are off, f*** it, it’s the apocalypse,” Republican strategist Rick Wilson told msnbc.

And endorse? Well, that might just be a strong word for this scenario.

“There’s a big difference between saying, ‘I endorse Donald Trump’ or issuing a one-line email statement, and getting in the campaign and being a surrogate,” Wilson added. “If it’s Trump, they hold their nose, they salute smartly and they try and reach out in four years.”

RELATED: Donald Trump says Middle East can wait, he'll learn it later

One of Trump's rivals echoed this idea last month, after the first debate.

“I would vote for the nominee, if it was Donald, I’d hold my nose and vote,” presidential hopeful Sen. Lindsey Graham said on MSNBC's "Morning Joe." “But Hillary Clinton would beat him like a drum.”

Spokespeople for other 2016 Republican candidates, including former Florida Gov. Jeb Bush, Louisiana Gov. Bobby Jindal, former New York Gov. George Pataki and former Texas Gov. Rick Perry did not respond to MSNBC's requests for comment on the pledge and whether they'd support Trump.

A spokesman for New Jersey Gov. Chris Christie would only say he had signed the pledge.