The Associated Press and Fox News both projected on Wednesday night that Republicans have won enough seats to control the US House.
A House Republican victory in Arizona, alongside a win in California earlier Wednesday, gave the GOP the 218 House victories that make up the majority, with nine races yet to be called.
Republicans had earlier gained control of the Senate from Democrats, securing a majority of at least 52-48 with one race uncalled.
Hours before securing their majority, House Republicans endorsed Speaker Mike Johnson (R-LA) to return for a second term. He still must notch a majority of votes from the 435-person chamber during a public floor vote in early January.
Johnson was first elected as House speaker in October of 2023, after lawmakers ousted then-Rep. Kevin McCarthy from the position.
Meanwhile on Wednesday, Senator Tom Cotton (R-AR) secured the position of Senate Republican Conference Chair, winning a competitive race against Senator Joni Ernst (R-IA), reported The Hill.
The role, which makes Cotton the party's chief messenger, was the only contested leadership position aside from the conference leader spot.
Cotton will succeed Senator John Barrasso (R-WY), who is moving up to become the Republican whip, replacing term-limited Senator John Thune of South Dakota.