As President Donald Trump rings in the New Year, he's also beginning to embrace a new friendship with a once-unlikely candidate: Sen. Lindsey Graham, R-South Carolina. Following a meeting with Republican senators about immigration policy at the White House Thursday, Trump spoke fondly of his onetime critic and rival for the 2016 Republican presidential nomination.

"Lindsey used to be a great enemy of mine, now he's a great friend of mine," Mr. Trump said. "I really like Lindsey. Can you believe that? I never thought I'd say that but I do like him a lot."

Keeping the tone light, Graham responded with a smile and a quick joke: "Thank you. I like me too, so we have something in common."

The other senators in the room chuckled, and Trump responded, "We all know that."

Mr. Trump's upbeat assessment of their relationship echoed comments that Graham made Sunday on Face the Nation. The senator explained why his once-fractious relationship with the president has mellowed.

"It's evolved because he is President of the United States, he beat me like a drum and I want to help him where I can because there's a lot on this man's plate," Graham said.

Asked about the criticism he'd leveled at Mr. Trump during the campaign, Graham brushed it off. "I said everything," he explained. "I said he was a xenophobic, race betting religious bigot. I ran out of adjectives. Well, the American people spoke. They rejected my analysis and he is now my President. I worked with President Obama where I could, with President Bush even though I supported Senator McCain. The bottom line, he is President of the United States. I've got to know him better. He asks a lot of good questions."

The friendly working relationship and regular golfing outings are a long way from how the two men used to view each other. During the campaign, Graham called Trump a "jackass" and a "kook," labeling him "crazy" and "unfit for office."

"I could make a million Donald Trump jokes, and I have, but our party and our country is going to have to up its game," the South Carolina Republican said at one point.

Graham wasn't the only one dishing out insults during the campaign -- Mr. Trump also did his share of bashing. Following the "jackass" comment, Trump spoke at a campaign rally in July 2015 about Graham.

"He doesn't seem like a very bright guy, okay?" Mr. Trump said. "He actually probably seems to me not as bright honestly as Rick Perry. I think Rick Perry is probably smarter than Lindsey Graham, but what do I know?"

In a particularly memorable moment, Mr. Trump then proceeded to read a telephone number to the audience and encouraged them to call it. The phone number belonged to Graham. Graham later turned the incident into a viral ad for his campaign in which he instructed viewers on how to destroy a cell phone (video below.)