Rep. Dave Trott (R-MI) is leaving Congress at the end of his term, he announced Monday morning, making him the third swing-district House Republican to declare his retirement in the past week alone.

Trott’s decision to leave is the latest sign that House Republicans are bracing for a brutal 2018 election — one that some of them aren’t so eager to face. And it opens up a competitive seat Democrats hope they can capture in a wave election.

President Trump won Trott’s suburban Detroit seat by 50% to 45%, about the same margin Mitt Romney carried it in 2008. But President Obama won it in 2008, and Democrats were already looking at Trott as a potential 2018 target.

“I have decided not to seek reelection in 2018. This was not an easy decision, but after careful consideration, I have decided that the best course for me is to spend more time with my family and return to the private sector,” Trott said in a statement.

Trott is already the fourth Republican from a competitive district to announce he’ll retire this year, and the third in just a week. Rep. Ileana Ros-Lehtinen (R-FL) announced earlier this year that she was done with Congress, and last week moderate Reps. Dave Reichert (R-WA) and Charlie Dent (R-PA) announced their retirements as well.

Republican strategists are bracing for more retirements in tough swing districts. Members tend to announce retirement plans either in early September, after they return from the August recess, or after the winter holidays after they have time to spend at home with their families.

“The [National Republican Congressional Committee] is looking forward to keeping his seat red in 2018. We will not let his hard work go to waste, and are confident this seat will remain under Republican control,” NRCC Chairman Steve Stivers (R-OH) said in a statement.

The Democratic Congressional Campaign Committee called his retirement “a tell-tale sign that running for re-election in Paul Ryan’s do-nothing Congress would have been an uphill climb not worth the effort” in a statement that promised to target the district next fall.

This story was updated at 1:20 p.m. EST.