Prior to the election, the Democrats had the smallest possible majority in the Senate: 51 of the 100 seats.
But early in the evening, they suffered a defeat when Republican Jim Justice took the Senate seat previously held by Joe Manchin, an independent senator who sided with the Democrats in votes, for West Virginia.
Later, another seat was turned when Democrat Sherrod Brown was defeated by Republican Bernie Moreno in Ohio.
At the time of writing, the Republicans have 51 seats in the Senate, while the Democrats have 42. Seven have not yet been decided.
Congress is the federal legislative assembly in the USA, based in the Capitol in the capital Washington DC. Its work runs in two-year periods, and the ongoing 118th Congress meeting started on January 3, 2023. The 119th meeting will be elected on November 5.
Congress consists of the Senate with 100 members, two from each state, and the House of Representatives with 435 seats, distributed in relation to the states' population.
In the Republican-led House of Representatives, there are currently 220 Republicans and 212 Democrats. Three seats are vacant. The even balance and divisions within each party make it difficult to pass laws and budget proposals.
In the Senate, the Democrats have 47 seats and the support of four independent members, giving the party a majority. The Republicans have 49 members.
Sources: USA's Congress, House Press Gallery
