South Carolina Sen. Lindsey Graham was pressed on his transition to an amicable relationship with President Donald Trump in spite of their often viral clashes before the 2016 election.

At one point during the campaign, Trump became so frustrated with Graham (R) that he shared the senator's cell phone number with the public.

CNN host Kate Bolduan on Friday asked Graham about several recent statements and decisions by Trump and why he continues to defend the president.

Graham said he still clashes with Trump from time to time but believes that Trump is trying to do the right thing for the country.

Happy Birthday, Mr. President! You’re keeping your promise to make America safer and more prosperous. And unfortunately for me, you’re doing all this without losing a step in your golf game!@realDonaldTrump #TrumpBirthday pic.twitter.com/PJRa54FVAP — Lindsey Graham (@LindseyGrahamSC) June 14, 2018

Bolduan asked about Trump's comment that President Obama was to blame for Russia annexing Crimea.

WATCH: Lindsey Graham Destroys Cell Phone After Trump Gives Out His Number

'Bring on the Recession': Bill Maher 'Hoping' for Economic Crash to Oust Trump

Graham said he doesn't agree with Trump on that point, but added that the president cannot be to blame for all the world's problems.

"When can you trust the words coming out of his mouth?" Bolduan asked, adding that Graham used to "hate" Trump.

"I know how the game is played, I don't give a damn," Graham said of being considered "two-faced" for working with Trump, but a "hero" for working with Obama.

"If you don't like me working with President Trump to make the world a better place, I don't give a s***," Graham said.

Watch the segment above. Relevant video begins at approximately the 11:00 mark.

'We Will Have a Red Tide': VA GOP Sen Candidate Corey Stewart Rips Tim Kaine, Praises Trump 'Successes'

Levin: IG Report Shows Strzok, Comey Interfered 'Worse Than the Russians Could Ever Dream Of'