Graham: GOP will get 'slaughtered' if Trump nominee
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Sen. Lindsey GrahamLindsey GrahamWeek ahead: Senate defense bill faces delay Week ahead: Uncertainty surrounds ObamaCare repeal vote Trump's DOJ gears up for crackdown on marijuana MORE (R-S.C.) argued Wednesday that if Donald TrumpDonald TrumpKushner says he did not collude with Russia, had no improper contacts Kushner: Meeting with congressional investigators went 'very well' The Hill's 12:30 Report MORE is the GOP nominee, Republicans will get "slaughtered" in the November election. 

Lambasting the outspoken Republican front-runner as an "opportunist," Graham argued that Trump would kneecap Republicans' hopes of winning back the White House. 
 
"I think he's a kook. I think he's crazy. I think he's unfit for office," Graham, a backer of Trump rival Jeb Bush, said on Fox News's "America's Newsroom."
 
"I'm a Republican. and he's not. He's not a conservative Republican, he's an opportunist," Graham said on the program. "He's not fit to be president of the United States."
Trump pushed back against the broadside, sending several tweets arguing that Graham had no support before ending his own White House bid in December and "no cred" to make the claims.
 
"I will beat Hillary easily," Trump insisted in one of his tweets before going after Fox News for airing remarks from one of his critics on the program.