WASHINGTON (CBSDC) – If Linsdey Graham thought he could shame Donald Trump into backing down from his rhetoric, he apparently thought wrong.

“Run for president, but stop being the world’s biggest jackass,” the South Carolina senator told “CBS This Morning.”

Trump fired back during a campaign rally in Graham’s home state, telling a South Carolina audience that Graham is a “stiff” who could never get a job in the private sector.

Trump then told a story about Graham calling him 4 years ago for a campaign endorsement and contribution. Trump claimed he went back through his phone records and found Graham’s private cell phone number. He showed the audience the number, written down on a yellow post-it note, and read the number aloud, encouraging everyone “let’s try it.”

RELATED: Trump: I Don’t Owe McCain An Apology

CBS News has confirmed the number does belong to Senator Graham. When CBSDC called the number, it went straight to voice mail, with a follow-up message that the mailbox is full.

Graham said he was particularly offended when Trump questioned the heroism of Arizona Sen. John McCain. McCain, a former Navy pilot, was shot down over Vietnam in 1967 and held prisoner by the North Vietnamese for over five years.

Trump drew the ire of many of his fellow Republican presidential candidates, who praised McCain’s military record.

Graham is a close friend of McCain. He argued that Trump’s comments do not reflect the beliefs of most Republicans.

“I hope there’s not much of a market for slandering POWs in my party,” mused Graham. “I don’t think there is.”

Iowa’s top newspaper The Des Moines Register called on Trump to drop out of the presidential race. Iowa holds the first-in-the-nation caucuses on February 1st, 2016.

RELATED: Des Moines Register Calls For Trump To Drop Out Of Presidential Race

Graham refused to repeat those calls.

“I don’t care if he drops out. Stay in the race. Just stop being a jackass,” he said.

Graham did say he believes Trump will not be able to overcome his POW gaffe and will be forced to end his campaign.

“The beginning of the end has arrived because he’s crossed the line with the American people that won’t be tolerated.”

RELATED: Donald Trump Dominating Presidential Contenders On Facebook


(TM and © Copyright 2015 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2015 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)