Republican Mike Gallagher to leave US House in April

Members of the U.S. House of Representatives leave the Capitol after a series of votes, in Washington

By Gram Slattery and Michael Martina

WASHINGTON (Reuters) -Republican U.S. Representative Mike Gallagher will step down from Congress on April 19. his office said on Friday, a move that will narrow Republicans' already razor-thin majority.

Gallagher, who chairs the House of Representatives Select Committee on the Chinese Communist Party, had already said he would not be running for re-election in November. But his decision to leave Congress early means the seat will be vacant for a time before the next election.

The Republicans currently hold a 219-213 House majority. However, Republican Representative Ken Buck is due to step down on Friday.

When Gallagher steps down, that will narrow the majority further to 217-213, meaning that Speaker Mike Johnson can only afford to lose one vote in order to pass legislation if Democrats remain united in opposition.

"I've worked closely with House Republican leadership on this timeline and look forward to seeing Speaker Johnson appoint a new chair to carry out the important mission of the Select Committee on the Chinese Communist Party," Gallagher said in a statement.

The fractious Republican majority has proven difficult to manage, and Johnson has repeatedly relied on Democrats to pass critical measures, like a government funding bill approved by the House on Friday. Anger over that led Republican hardliner Representative Marjorie Taylor Greene to threaten to call a vote to oust Johnson as speaker, six months after the party booted its prior leader, Kevin McCarthy.

(Reporting by Gram Slattery; Editing by Scott Malone)