Over decades, Graham has painstakingly built a reputation in the Washington establishment as a national security leader willing to buck political convention on at least some issues -- in the style of his longtime mentor Sen. John McCain of Arizona, who died in August 2018.
As he seeks a fourth term this year, however, he's all but dropped his bipartisan bonafides on heated issues like immigration to double down on Trump-flavored appeals to the Republican base. Ahead of the 2020 election, Graham has now staked his legacy on an infamously mercurial president.
His transformation helps explain why Senate Republicans have remained so unified behind Trump. Despite polls showing the country as a whole closely divided on impeachment, that's not the case in deep-red states like South Carolina. The cold reality for Graham and other ranking Republicans is that Trump is far more popular back home than they are.
When Trump was elected, many Republican officials thought they were the party and he, a newcomer to the GOP, was the interloper. Instead, they've learned a hard lesson: It's been Trump's party all along.
Graham declined a request to be interviewed for this article.
Trey Gowdy, the former South Carolina congressman, and a Trump defender, explained Graham's calculation as realpolitik.
"I do get the national narrative that they think he is somehow becoming this sycophant-ish disciple of President Trump," Gowdy said. "But it's about having a relationship where you can go express those differences. If you don't have a relationship, you can't be heard at all."
John Weaver, a longtime McCain adviser, doesn't buy that "adults in the room" defense. "Imagine if you were a passenger on the Titanic, then, after the ship hit the iceberg, you handcuffed yourself to the railing and threw the key into the ocean," Weaver said. "That's the danger for them; they've handcuffed themselves to this man, to Trump."
It was during the country's last impeachment, of President Bill Clinton, that Graham first met McCain, forging a long friendship. McCain said he was "so impressed" by Graham's performance as one of the House managers in the 1999 Senate trial that he quickly asked the then-congressman to back him for the Republican Party's nomination in the 2000 presidential election.
"I said, 'Look, I'd appreciate it if you'd help me in the campaign,'" McCain recounted in 2016 as he returned the favor by campaigning for Graham in New Hampshire during Graham's quixotic presidential bid that year.