Senator Lindsey Graham is fighting President Donald Trump’s impeachment case on Twitter and every media outlet that will have him. Senator Mitch McConnell is swatting down Democratic demands and pledging to acquit the president.

But behind the scenes, Sen. Mike Lee is quietly playing a crucial role coordinating with Trump and his legal team ahead of the impeachment trial.

The Utah Republican is working with the White House to track the wide-ranging viewpoints within the Republican Senate majority, including his Utah colleague and impeachment wild card Mitt Romney. That relationship could prove critical when the Senate considers difficult votes on witnesses or other motions, and ultimately on the president’s acquittal or conviction.

And though Lee is staying away from the cable news food fights that some of his colleagues are fixtures on, he’s not exactly urging a dulcet tone from Trump.

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“He has every reason to be confident about this, every reason to be unapologetic and defiantly confident about his case. Because he has a really good case,” Lee said in an interview as the Senate left for the winter holidays late last week. “I have suggested all along: If [House Democrats] are going to do this, steer right into the wind.”

As soon as Speaker Nancy Pelosi announced an impeachment inquiry this fall, Lee began regularly talking with the president and White House counsel Pat Cipollone about how to plan for the storm. Importantly, Lee has helped advise Trump and his team that the Senate shouldn’t just try to dismiss the impeachment charges but should instead hold a trial to exonerate him.

Some of Lee’s colleagues have suggested it was inappropriate for Trump to urge the Ukrainian president to investigate Joe Biden. The second-term senator argues that the president is squeaky clean, and that unless new information comes out at the trial, he already knows how he will vote on charges Trump abused his office and obstructed a congressional investigation.

“What he did was not impeachable. It was not criminal,” Lee said. “And I don’t think what he did was even wrong.”

But now, Lee has emerged as one of the de facto leaders of the case to acquit the president. It’s the latest example of the libertarian-leaning conservative’s continued evolution as a senator — from a hard-liner eager to buck leadership to a powerful ally of a GOP president he once shunned.

Once known as a key instigator in the failed 2013 fight to defund Obamacare, Lee has become an integral cog in the Senate GOP machinery, at least when it comes to impeachment. He’s met with McConnell about impeachment strategy and praises the posture of a GOP leader he once clashed with regularly.

Republicans who have fought with Lee in previous instances are delighted to have him as an ally at such a critical moment.

“He’s offended by the process in the House and he wants to make sure the Senate trial is not turned into a circus,” said Graham, who has clashed with Lee on foreign policy and immigration. He’s a senator “we all respect and the White House sought out his views … he’s been very constructive.”