The Republican Party has wrested control of the US Senate from the Democrats, with at least 51 seats in the 100-member upper house of Congress, US networks projected early on Wednesday.

It gives the GOP a major power centre in Washington and a lead role in confirming the next president’s cabinet, as well as any Supreme Court justice if there is a vacancy.

The last time the Republicans had a majority in the Senate was January 2021.

The US Capitol is divided into the House of Representatives - where all 435 seats are up for grabs - and a 100-member Senate, which has 34 seats at stake this year. Congressional elections run alongside the White House race.

Jim Justice, the sitting Republican governor of West Virginia, delighted Republicans early in the night when he emerged as an easy victor in the Senate race to replace retiring moderate Joe Manchin, an independent who voted with the Democrats.

Ohio then moved into the Republican column after longstanding Democratic Senator Sherrod Brown was defeated by Bernie Moreno, a Trump-endorsed businessman and the son of a one-time high-ranking Colombian government official.

Democrats were looking to mitigate losses with gains in Texas and Florida, but conceded both as the sitting Republicans notched easy wins.

Nonpartisan political finance monitor OpenSecrets reports that US$10 billion has been spent on candidates for Congress this cycle - a touch less than in 2020 but almost twice as much as the US$5.5 billion price tag for the 2024 White House race. (Agencies)