Republicans have scored an early victory in the race for control of Congress: The state's current governor, Jim Justice, won a formerly Democratic-leaning seat in West Virginia.

In addition to the presidency, all 435 seats in the House of Representatives and 34 seats in the Senate are up for election on election day.

The Republicans currently have the majority in the House of Representatives. The judiciary's projected victory creates a 50-50 split in the Senate. However, the results for the other seats are still pending.

The party that wins a majority on both sides of Capitol Hill will have greater influence in pushing its own agenda, regardless of who sits in the White House.

A party that controls the House, Senate and White House would have broad power to pass laws and implement the president's partisan agenda.

The Senate seat in West Virginia was taken over by Republicans following the resignation of former Democrat Joe Manchin, who frequently clashed with members of his own party before becoming an independent.

The winner, Justice, had been a Democrat himself before switching parties to Republican at a Trump rally in 2017.

Republicans were also expected to retain control of a Senate seat in Florida.

Incumbent Rick Scott, also a former governor, was first elected six years ago. He was running against former Miami congresswoman Debbie Mucarsel-Powell, a Democrat who immigrated from Ecuador as a child.

At a victory rally, Scott predicted that Republicans would capture the majority in the Senate and that he would be elected Senate majority leader.

“Florida is the center of the Republican Party of this country,” he told the crowd. “Washington can learn a lot from what we have done here in this great state.”

Democrats had an open seat in Delaware, a state that President Joe Biden represented as a senator for 36 years.

Lisa Blunt Rochester, currently serving her fourth term in the House of Representatives, will be the fourth Black woman to serve in the Senate.

Other contests that would take control of the upper chamber of Congress are in Arizona, Pennsylvania, Montana, Michigan, Nevada, Nebraska, Texas and Wisconsin.

Both parties are also vying for control of the House of Representatives, although the balance of power there won't be known for several days.

The vast majority of parliamentary elections take place in “safe districts” – regions where a party is almost certain to win. But a handful of other races in swing districts could decide who controls Washington DC.

Many states have House races that could tip the balance, with closely watched elections in California, New York, Washington, Maine and Alaska.

North America correspondent Anthony Zurcher breaks down the race for the White House in his twice-weekly newsletter, US Election Unspun. Readers in the UK can Register here. People outside the UK can do this Register here.