Republicans cemented a slim majority in the US House of Representatives on Wednesday, over a week after the US held nationwide midterm elections.

Vote counting is ongoing in several tightly-contested races, particularly in the US's most populous state of California, but Republicans were able to claim their 218th seat Wednesday evening, according to an Associated Press tally. Democrats have secured 210 seats so far with seven races still uncalled.

It could be days or weeks for final decisions to be reached in those contests, but the incoming House is slated to hold one of the slimmest majorities in modern history.

Democrats were able to successfully defend their majority in the Senate, perhaps even adding a seat depending on the Dec. 6 runoff in Georgia, and have staved off worst-case scenarios in the House that predicted dozens of seats falling to Republicans in what is colloquially known as a "red wave."

With underwhelming showings in both the House and Senate, Republicans are set to face an internal reckoning as they head into the 2024 presidential contest, which former President Donald Trump formally entered on Tuesday.