Democrats are projected to wrest control of the US House of Representatives from Republicans and have secured a majority in the Senate, setting up a legislative check on President Donald Trump's administration for the first time since his return to the White House in January 2025.

Democrats have secured 51 seats in the Senate against 39 for Republicans, crossing the threshold required for a majority, according to Associated Press election results. Ten seats remained uncalled in the AP's latest results update.

The Democratic lead marks a shift from the early results, when the party was ahead 45 to 35, with 20 seats yet to be called. The latest count indicates that Democrats have secured enough seats to take control of the upper chamber.

The shift would end the Republican Party's ability to pass legislation solely with its own support in the lower chamber. The change in control is scheduled to take effect on January 3, 2027.

The results represent a major setback for Republicans, who entered the midterm elections controlling both chambers of Congress. A Democratic-controlled Congress would be able to block legislation, intensify congressional scrutiny and initiate investigations into administration policies.

The election outcome comes amid voter concerns over the cost of living and the economic impact of the administration's policies, alongside opposition to the US war in Iran. Trump's approval ratings had fallen in the weeks preceding the election, while Republican candidates faced pressure over their association with the president.

A Democratic-controlled House and Senate would complicate Trump's legislative agenda during the final two years of his presidency. The administration would retain control of the executive branch and the presidential veto, but Democrats would gain greater influence over legislation, congressional oversight and investigations.

The Republican-controlled Congress has so far largely backed Trump's agenda, confirming his cabinet nominees, approving his signature tax legislation and refraining from imposing significant restrictions on his tariff policies and military operations against Iran.

The immediate political challenge for Republicans will be to advance the president's remaining legislative priorities before the new Congress takes office in January. GOP lawmakers are likely to face greater pressure to push through proposals that could become difficult to pass once Democrats assume control of both chambers.

Republicans will retain control of Congress until the current session ends and the newly elected members take office in January.