Rep. Ken Buck (R-CO) announced on Tuesday that he will resign from Congress at the end of next week, further eroding the already razor-thin GOP majority in the House of Representatives.

Buck made his announcement Tuesday in a press release shared on X.

Buck was one of eight Republicans who voted in favor of the motion to vacate former House Speaker Kevin McCarthy (R-CA). He also opposed Judiciary Chair Jim Jordan’s (R-OH) bid to be McCarthy’s successor and announced soon thereafter that he would not seek reelection. In late December, Rep. Lauren Boebert (R-CO) revealed she would be running for reelection in Buck’s district, blaming Democrat “dark money” for trying to unseat her in the Third Congressional District, which she currently represents.

Republicans will hold a five-seat majority of 218-213 once Buck is gone. His looming resignation is accompanied by several other Republican departures in the 118th Congress, including those of McCarthy and expelled Rep. George Santos (R-NY).

After being ousted from the speakership in a motion to vacate in October, McCarthy left Congress in December. McCarthy’s exit followed Santos’s expulsion on the heels of a damning November ethics report about his campaign and a 23-count federal indictment in October. And former Rep. Bill Johnson (R-OH) resigned from his seat in January. It remains vacant.

Santos’s exit, which marked the first time a member has ever been expelled based merely on criminal allegations and not a conviction, allowed Democrats to seize his seat in a special election in February, which Rep. Tom Suozzi (D-NY) won; they held 212 seats before that.