Rep. Steve Stivers, R-Ohio, said on Monday that he’s resigning on May 16, joining an ever-growing list of GOP politicians jumping ship as Donald Trump tightens his grip on the party.

Stivers will be joining the Ohio Chamber of Commerce as president and CEO.

Stivers’ replacement will be decided by a special election organized by Gov. Mike DeWine, a Republican. The district tilts conservative, voting 56% for Trump and 63% for Stivers in 2020.

His new job probably means he won’t compete for Ohio’s Senate primary opened by retiring Sen. Rob Portman.

Stivers joins an increasing list of GOP lawmakers quitting the House. Five other GOP House members have announced they won’t be seeking reelection, although two are pursuing higher office.

Three Democrats have confirmed they’ll retire, which along with three who quit to join the Biden administration makes the parties’ losses equal. Like the Senate, the House is running on a razor-thin Democratic majority, only 218 to 212.

Stivers’ resignation will drop that number to 211. He presided over the National Republican Congressional Committee when it lost 40 seats in the GOP’s disastrous 2018 midterm.

Stivers’ lack of specificity in his resignation announcement makes speculating on his motives difficult. The Republican party, however, is facing unprecedented tension as still-popular Trump fights traditionalists for control.