Washington (CNN) No one has been a bigger convert on President Donald Trump than Lindsey Graham.

Way back in 2015, when the South Carolina senator was challenging the billionaire businessman for the Republican presidential nomination, Graham said this of Trump: "You know how you make America great again? Tell Donald Trump to go to hell." And, oh yeah, Graham also called Trump a "race-baiting, xenophobic, religious bigot."

Fast-forward to the here and now. "To every Republican, if you don't stand behind this President, we're not going to stand behind you," Graham said in South Carolina recently . "This is the defining moment of his presidency. It's not just about a wall. It's about him being treated different than any other president." (In 2017, Graham said he was "the happiest dude in America right now," adding: "We have got a President and a national security team that I've been dreaming of for eight years.")

Graham's 180-degree turn on Trump has been particularly pronounced of late, as he has carefully calibrated his responses to the President's attacks on the late John McCain -- Graham's best friend in the Senate. After taking heat for his lackluster original response to Trump's attacks, Graham was more full-throated in his response on Wednesday ; "When it comes to criticizing Sen. McCain and his service, I think that's a huge mistake," Graham said of Trump.

On Thursday morning, we got hard evidence that proves a) why Graham is playing so nice with Trump and b) that it's working. A new Winthrop Poll shows that almost three in four Republicans and Republican leaners (74%) approve of the job that Graham is doing in the state. That's similar to Trump's 82% job approval rating among South Carolina Republicans in that same poll.

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