Democrats have won control of the US House of Representatives after securing a majority in the Senate, ending Republican dominance of Congress and setting up a legislative check on President Donald Trump's administration during the final two years of his presidency.

Democrats have secured 224 seats in the House against 133 for Republicans, crossing the 218-seat threshold required for a majority, according to Associated Press election results updated at 1245 IST. The party has gained 25 seats from Republicans, with several constituencies yet to be called.

In the Senate, Democrats and independents who caucus with them have secured the 51 seats needed for a majority, overturning Republican control of the upper chamber.

The Democratic victory extended into traditionally Republican states, with the party winning Senate races in Texas, South Carolina, Iowa and Kansas, according to AP.

In Texas, Democrat James Talarico defeated Republican Ken Paxton, ending a more than three-decade period in which Democrats had failed to win statewide office. Democrat Josh Turek defeated Republican Ashley Hinson in Iowa, while Adam Hamilton defeated incumbent Senator Roger Marshall in Kansas.

Democrats also secured victories in Ohio, North Carolina, Maine and Georgia. In the House, the party gained Republican-held seats across several states, including Iowa, Texas, Florida and Pennsylvania.

The election outcome comes amid widespread voter dissatisfaction over high prices, the war in Iran and concerns about government corruption.

According to an AP voter survey, about three-quarters of voters described the US economy as either not so good or poor, while roughly eight in 10 said inflation had caused severe or moderate financial hardship for their households.

Around three-quarters of voters also expressed anger or dissatisfaction with the country's direction, underscoring the economic and political pressures facing the Trump administration.

The results are expected to significantly constrain Trump's legislative agenda, with Democrats gaining control over government spending negotiations, congressional committees and investigations into administration policies.

Democratic leaders have indicated that they intend to intensify scrutiny of the administration, while Trump has signalled that he would use his presidential veto against legislation he opposes.