WASHINGTON — Rep. Justin Amash, R-Mich., resigned from the conservative House Freedom Caucus late Monday, NBC News confirmed Tuesday.

Amash is the only Republican in the House to call for impeachment proceedings against President Donald Trump. Currently, a quarter of the House Democratic caucus support opening such an inquiry.

Amash, 39, identifies as a libertarian Republican and is considered among the most conservative members of the House, in which he’s served in since 2011. He helped found the Freedom Caucus in 2015, which is chaired by Rep. Mark Meadows, R-N.C., a frequent defender of the president.

“I have the highest regard for them, and they’re my close friends,” Amash told CNN reporter Haley Byrd on Monday evening. “I didn’t want to be a further distraction for the group."

Amash's chief of staff Poppy Nelson confirmed the move to NBC Tuesday.

Meadows said that he had spoken to Amash on Monday, and that Amash did not attend the group's weekly meeting that evening.

“Justin and I have had conversations over the last several weeks and discussed the mission of the Freedom Caucus, which is to represent the millions of Americans who feel like Washington, D.C., has forgotten them," Meadows said. "He felt like his continued affiliation with the caucus would be a distraction, and that it was best for all concerned that he step aside.”

Conservative groups like the Club for Growth, Heritage Action for America and Americans for Prosperity have awarded Amash lifetime ratings of more than 85 percent. But that hasn’t stopped the congressman from bashing Trump publicly.

Last month, Amash posted a series of tweets about his conclusions from reading special counsel Robert Mueller’s redacted report on Russian interference in the 2016 election, saying, “Trump engaged in specific actions and a pattern of behavior that meet the threshold for impeachment.”

The tweets led to Amash receiving his first official 2020 GOP primary challenger — Michigan state Rep. Jim Lower, who said in a statement that he is a “pro-Trump, pro-life, pro-jobs, pro-2nd Amendment, pro-family values Republican,” and that Amash's remarks “show how out of touch he is with the truth, and how out of touch he is with people he represents.”

Amash is often viewed as an outlier within his own conference, as House Minority Leader Kevin McCarthy, R-Calif., noted Tuesday. "Justin Amash can determine his own future, but I think in a philosophical basis he is probably in a different place than a majority of Republicans," McCarthy said at a GOP leadership press conference when asked about the Michigan congressman's resignation from the Freedom Caucus.

In February, Amash was one of 13 Republicans to join 232 Democrats in favor of a bill to overturn Trump’s emergency declaration to build a border wall. A month later, he defected again and joined Democrats in a vote to override the president’s veto of that measure. And in December, Amash was one of only eight Republicans to vote against a spending bill that would have provided $5.7 billion in border wall funding. According to FiveThirtyEight, Amash voted about 54 percent of the time with Trump in the first two years of his presidential term.