As well as the White House, Democrats and Republicans are locked in a tight race for control of the US Senate. Republicans hold a 53-47 majority in the upper chamber of Congress, meaning the Democrats are seeking a net gain of four seats.
Five seats, including some tight battleground contests in Georgia and North Carolina, are yet to be decided. Democrats are also fighting to maintain their majority in the lower chamber, the House, and are ahead in the polls.
But with many votes still to be counted, the final result of both races may not be known for some time. This year’s congressional election is running alongside the battle for the White House between Donald Trump and his Democratic challenger Joe Biden.
A Democrat-controlled House and Senate would have the power to obstruct the plans of a second-term President Trump, or push through the agenda of a first-term President Biden.Of the 35 Senate seats up for grabs, 23 are Republican-held and 12 are Democrat. Senators serve six-year terms, and every two years a third of the seats are up for re-election.