Asked about how he had balanced his friendship with McCain with his growing relationship with Trump over the past year and half, Graham acknowledged that it had been "challenging."

"He said help him where you can, just don't get sucked into all of his bullshit," Graham told reporters.

"I said 'roger.' So I'm going to help [Trump] where I can and not get sucked into all the other drama," Graham continued. "John felt like his view of the world had to be reinforced and that the conflict between him and the president has been difficult."

McCain and Trump had a rocky relationship for years, with the then-GOP presidential candidate sparking backlash during his 2016 campaign by appearing to mock McCain for getting captured during the Vietnam War.

"I like people who weren't captured," Trump said in July 2015.

For a months-long stint in 2016, McCain refused to answer questions from reporters around the Capitol about Trump.

The relationship didn't appear to recover once Trump took over the White House. The two men were on opposite sides on key issues, including foreign policy and immigration.

McCain, as chairman of the Senate Armed Services Committee, had been one of Trump's most vocal GOP critics on national security, with the two men sharing fundamentally different views.

Despite being absent from Washington since late last year while battling brain cancer, McCain came out against Trump's pick of Gina Haspel to lead the CIA and signed on to a Russia sanctions bill introduced earlier this month.

McCain didn't directly mention Trump during his farewell statement released on Monday, two days after he died of brain cancer, but appeared to take an indirect shot at the administration.

"We weaken our greatness when we confuse our patriotism with tribal rivalries that have sown resentment and hatred and violence in all the corners of the globe,” McCain said in the statement released by his Senate office.

"We weaken it when we hide behind walls, rather than tear them down, when we doubt the power of our ideals, rather than trust them to be the great force for change they have always been."