Republicans secured a critical victory in West Virginia on Tuesday, flipping a US Senate seat from the Democrats as they battled for control of Congress in elections that will shape the legislative landscape for the next presidential term.

West Virginia Governor Jim Justice, a former Democrat who became a Republican shortly after his 2016 election, defeated Democrat Glenn Elliott in a contest to replace retiring independent Joe Manchin. Manchin, a centrist who often sided with Democrats, left the seat open, which Republicans were widely expected to capture.

This win brings Republicans closer to regaining a majority in the Senate, erasing the Democrats' slim 51-49 margin. Republicans now need only one more seat to reclaim the Senate and are focusing on tight races in Montana, Ohio, and potentially Wisconsin, Pennsylvania, and Michigan.

Meanwhile, all 435 seats in the House of Representatives are up for grabs, with control too close to call. Although Democrats currently hold a minority, they are hopeful of flipping at least four seats to regain the majority in the House, with pivotal races in New York and California potentially extending the final outcome by days.

The stakes are high, with Republicans aiming for a majority that would enable them to block key aspects of Democrat Kamala Harris' potential agenda, should she win over Donald Trump in the presidential race.

Control of the Senate is particularly important, as it would allow Republicans to halt appointments and policy initiatives, while the House, responsible for revenue-raising bills, could shape budget priorities.

With an estimated $10 billion spent on congressional races this cycle, according to OpenSecrets, spending remains close to 2020's record.

Trump leading in presidential race

The early hours of voting show former US President Donald Trump leading the polls in terms of the electoral college 101 to Vice President Kamala Harris' 71, according to The Associated Press, with battleground states remaining contested, namely Michigan, Georgia, Virginia, and North Carolina.

As votes started pouring in, Republican nominee Donald Trump swept across several states, winning Indiana, Kentucky, West Virginia, Tennessee, South Carolina, Alabama, Oklahoma, Florida, Arkansas, and Mississippi, while garnering a notable lead in Texas, Georgia, Virginia, Missouri, Ohio, and North Dakota.

Harris, meanwhile, has won Delaware, Vermont, Maryland, Connecticut, Rhode Island, and Massachusetts while maintaining a sizeable lead in Kansas, Illinois, Michigan, Pennsylvania, North Carolina, New Jersey, and New Hampshire.