Rep. Mike Gallagher (R-WI) will retire from the House months before his term ends next year, setting up a scenario in which House Speaker Mike Johnson (R-LA) could have a one-seat majority.

Gallagher will step down effective April 19, making him the latest in a string of Republicans who have announced they would leave the House early and further narrowing the party’s slim control in the lower chamber. Gallagher’s departure also deals a blow to GOP leadership because the Wisconsin Republican sits as the chairman of the Select Committee on the Chinese Communist Party.