In this case, the reaction amounts to more of an acceleration than anything else. Michigan state representative Jim Lower had already planned to challenge Justin Amash in a primary next year. The incumbent’s tweets endorsing an impeachment of Donald Trump made a perfect point of entry for Lower, however:

Two days after Republican U.S. Rep. Justin Amash said President Donald Trump “engaged in impeachable conduct,” a state representative from Montcalm County has announced he will attempt to unseat Amash in the August 2020 Republican primary.

“I am a Pro-Trump, Pro-Life, Pro-Jobs, Pro-2nd Amendment, Pro-Family Values Republican,” Jim Lower, R-Greenville, said in a statement. “Congressman Justin Amash tweets yesterday calling for President Trump’s impeachment show how out of touch he is with the truth and how out of touch he is with people he represents.”

Lower, 30, who was elected to the Michigan House of Representatives in 2016, said he has been organizing his campaign against Amash for the past two months and planned to announce his candidacy on July 4 but moved up the timeline after Amash’s comments.

Lower had already begun organizing and fundraising for the challenge, according to Michigan Live. He planned for an Independence Day rollout of the campaign, but Amash’s sudden injection into the national narrative gave Lower a perfect MAGA moment.

Running for the nomination as a full-MAGA candidate is probably a good idea, at least in the primary. Michigan’s 3rd congressional district has an R+6 Cook index, and the seat has been Republican since 1993 — and mostly Republican before that for the entire 20th century. Democrats have only held that seat for eight terms out of 50 in that century, although the district has been remapped several times during that period.

That strategy looks even more solid in presidential years. It has gone to the GOP nominee every time since 1992, even while Democrats won the state as a whole. Donald Trump won this district by ten points, 52/42, outpacing not just the state as a whole but also the district’s own Cook index rating.

Amash has won five terms in this seat, so he’s not just a flash in the pan for MI-03. It’s tough to imagine that his approach to impeachment will sit well within a district that Trump carried by ten points in 2016, but it’s not clear that will undermine the advantages his incumbency carries either. One such advantage — the tacit or active support of his political party — could be notably absent after Amash’s weekend tweets.

Lower plans to campaign against Amash as someone who has fallen in with “radical liberals,” which might be tough for Amash to counter in this instance. The Washington Post tries to help out Amash with a spot fact-check:

The state lawmaker, who became a county commissioner in 2011 at the age of 21, accused Amash of joining hands with “radical liberals” — naming Tlaib in particular — “to try and bring down our President.” On most issues, a chasm separates Amash from the liberal firebrand.

No kidding, but that is Lower’s point. The question is: Does it on the one that matters to Trump voters? Lower plans to find out, and Amash might discover that his own actions have more consequences than he might have initially considered.

Addendum: I largely agree with Erick Erickson on Amash generally. Amash has been an independent voice for conservo-libertarian principles who has not been willing to put party over principle, and we do need more people like that in Congress. That doesn’t mean, however, that his call for impeachment can’t be part of the judgment that people make on Amash, especially in a primary fight.