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Sen. Lindsey GrahamLindsey GrahamTrump’s UN pick threads needle on Russia, NATO Haley slams United Nations, echoing Trump Haley to question US funding of UN: report MORE (R-S.C.) is remaining tight-lipped about whether he would vote for Donald TrumpDonald TrumpDorgan: Democrats can fix their blues in red states by talking to more Americans Democrats opposition to Trump will extend well beyond the boycott Trump team prepares dramatic cuts MORE if the billionaire were to become the Republican presidential nominee.
"I'll cross that bridge when I get there, but we'll lose," he said when asked if he would vote for Trump as GOP nominee.
"No, we won't lose," Graham added. "We'll get slaughtered."
Graham's comments come after Trump carried more than 45 percent of the vote in Tuesday night's Nevada Republican caucuses.
Asked about Trump's win, the South Carolina senator, himself a presidential contender this election cycle, said he thinks the real estate mogul "has momentum," and that Republicans have until early March to try to stop him from becoming the nominee.
Graham has been one of Trump's most vocal critics, both during his own bid and as a surrogate for former Florida Gov. Jen Bush, who recently ended his White House run.
While Trump has yet to pick up a single Senate endorsement and many vulnerable lawmakers are wary of tying themselves to the GOP front-runner, Republican senators have publicly stuck with the strategy that they'll support the eventual nominee.
Trump picked up his first two congressional endorsements on Wednesday, both from the House.
Graham has given little indication he'll endorse another candidate and said Wednesday that he was "disappointed" Sen. Marco RubioMarco RubioTop Dem: Don’t bring Tillerson floor vote if he doesn’t pass committee Booker to vote against Tillerson Rubio wades into Trump-Lewis feud MORE (R-Fla.) isn't a stronger challenge to Trump.
Rubio came in second place in the Nevada caucuses behind Trump.