Michigan Rep. Justin Amash announced Thursday that he was leaving the GOP after growing "disenchanted" with and "frightened" by party politics.
"Modern politics is trapped in a partisan death spiral, but there is an escape," said Amash, who last month became the first congressional Republican to conclude that President Donald Trump has engaged in "impeachable conduct."
His conclusion came after he read special counsel Robert Mueller's redacted report on Russian interference in the 2016 election, he tweeted in a widely circulated thread.
Trump hit back at Amash on Twitter at the time, calling him a "loser."
"Never a fan of @justinamash, a total lightweight who opposes me and some of our great Republican ideas and policies just for the sake of getting his name out there through controversy," Trump wrote at the time.