Rep. Justin Amash of Michigan, the first Republican in Congress to accuse President Trump of impeachable conduct, is facing a primary challenge.

State Rep. Jim Lower announced Monday he's running for the western Michigan seat. The announcement came two days after Amash sent a series of tweets , concluding that special counsel Robert Mueller's investigation into Russian meddling in the 2016 election reveals Trump "engaged in specific actions and a pattern of behavior that meet the threshold for impeachment."

The 30-year-old Lower, of Greenville, says he made the announcement earlier than planned after Amash attacked Trump.

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Lower calls himself a "pro-Trump, pro-life, pro-jobs, pro-Second Amendment, pro-family values Republican." He is in his second term in the Michigan House after working as a legislative staffer and political consultant.

Amash was first elected in 2010 and overcame a 2014 primary challenge.

In a series of tweets on Saturday, Amash wrote he had read the full report by special counsel Robert Mueller and had concluded the president's conduct met the "threshold for impeachment."

"Under our Constitution, the president 'shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery or other high Crimes and Misdemeanors,'" Amash wrote Saturday. "While 'high Crimes and Misdemeanors' is not defined, the context implies conduct that violates the public trust."

The president responded to Amash on Sunday morning, calling him a "loser" and "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."

Rep. Adam Schiff, chairman of the House Intelligence Committee, called Amash courageous for his criticism.

"He showed more courage than any other Republican in the House or Senate," Schiff told CBS News "Face the Nation" on Sunday. "But what may be pushing us in the direction of impeachment in any event has less to do with Justin Amash and more to do with the fact that the administration is engaging in a maximum obstructionism campaign against Congress."