(CNN) —

Sen. Lindsey Graham is frantic.

“He’s making the biggest mistake of his presidency,” the South Carolina Republican tells reporters in the halls of Congress.

President Donald Trump is annoyed.

“I think Lindsey should focus right now on Judiciary – like the Democrats – the do-nothing Democrats,” he tells reporters in the East Room of the White House.

Graham is warning about terror attacks.

“He will have American blood on his hands if he abandons Kurds because ISIS will come back.”

Trump doesn’t want to hear it.

“Lindsey should focus on the do-nothing Democrats.”

Watching them launch sharp barbs at one another up and down Pennsylvania Avenue, it’s hard to believe Graham is one of Trump’s most loyal allies. It’s like a time warp – back to their campaign rivalry.

“I don’t think he has the temperament or judgment to be commander in chief,” Graham told me in 2016, as he announced he was so disgusted with Trump, he was not going to vote for him for president.

As it turns out, 2016 Graham warned voters about exactly what 2019 Graham is apoplectic about now: that Trump’s promise to withdraw troops from the Middle East will make America less safe.

“For God’s sakes, pick somebody who is worthy of the sacrifice of those who are fighting this war and who actually knows how to win, and I don’t believe that’s Mr. Trump,” Graham begged voters during a 2016 campaign primary debate.

It’s complicated

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