A voter visits a polling station to cast their ballot with a child during the US midterm elections in West Columbia, South Carolina, US, on November 3, 2026. — Reuters Economic discontent, high energy costs, Iran war weigh on Republicans. More than 57m voted early, with campaign advertising topping $11b. NY voting machine malfunctions fuelled unfounded fraud claims.

Millions of Americans voted Tuesday in midterm elections seen as a referendum on Donald Trump, which could wrest control of Congress from Republicans and impose major constraints on the president for the remaining two years of his term.

Polls predict Democrats will win a majority in the House of Representatives and could also seize control of the Senate, capitalising on voter resentment over an unpopular president, soaring energy costs and the ongoing conflict with Iran.

A Republican loss of the House would give Democrats the power to block Trump's legislative agenda and launch sweeping investigations into his administration.

A Senate defeat would threaten his ability to appoint Supreme Court justices and senior officials, while signalling that Trump's overwhelming dominance of US politics may finally be waning.

Gabrielle Schlueter, a 69-year-old retiree casting her ballot in Atlanta, Georgia, told she was voting for Democrats across the board.

"The way the country is going is not very good. The economy. The prices of everything," Schlueter said. "Healthcare. I'm not suffering from it, but others shouldn't have that worry." Trump, 80, defended his record in a final television phone-in appeal to voters on Tuesday, saying he had rebuilt the country through his crackdown on immigration, war on Iran and tariffs.

"We have to keep America great. We're great now. We were terrible two years ago," Trump told "Fox & Friends".

All 435 seats in the House and 35 of the 100 Senate seats are being contested, along with governorships in 36 states. Democrats need just three additional seats in the House and a net gain of four in the Senate to take control of both chambers from Republicans.

Trump returned to office promising to bring down prices, but inflation, tariffs and fuel costs driven up by the conflict in the Middle East have squeezed American households.

Economic discontent Republicans insist Trump's tax cuts and tough stance on immigration will benefit voters. They have portrayed Democratic candidates as left-wing radicals, a message that appears to have resonated with some voters.

"Democrats used to be decent in the past, but they became very socialist," Maru Restrepo, a 70-year-old voter of Colombian origin, told in Miami. "The Republicans maintain America's values. They love the country." At his final public campaign appearance on Monday, Trump barely addressed the election, instead delivering a rambling speech about his troubled renovation of Washington's Reflecting Pool. Senate Democratic leader Chuck Schumer branded it a "pathetic closing message".

Republicans currently hold a 53-47 majority in the Senate, but the electoral battleground has extended into states once considered reliably conservative, including Kansas, Texas, Iowa, Ohio and Alaska.

Democrats must also defend competitive seats, including in Michigan, where a bitter internal dispute saw Congresswoman Haley Stevens endorse Republican Mike Rogers rather than the Democratic nominee, Abdul El-Sayed.

Decision Desk HQ's final forecast projected Democrats would win 241 seats in the House against 194 for Republicans, and a narrower 52-48 majority in the Senate. Disputed results?

More than 57 million Americans had already voted early before Tuesday, signalling high voter engagement.

The campaign has attracted more than $11 billion in political advertising, while billionaire Trump ally Elon Musk has poured hundreds of millions of dollars into Republican efforts.

As soon as polling stations close, concerns are expected to mount over whether Republicans will accept the results.

Trump, who tried to overturn his defeat in the 2020 presidential election, has repeatedly alleged widespread voter fraud and accused Democrats, without evidence, of cheating.

Voting machines malfunctioned in a fiercely contested House race in New York state on Tuesday, prompting right-wing influencers to make unfounded allegations of fraud even as local election officials insisted all ballots would be counted.

The Justice Department, led by Trump's former personal lawyer, has already sued to potentially block certification of Alaska's Senate race if Republican incumbent Dan Sullivan narrowly loses, but a court rejected the effort.

The Supreme Court also rejected on Monday an emergency bid to force California to set aside mail-in ballots cast by more than 20,000 people because they might not be US citizens.

Trump, who will watch the midterm results at the White House on Tuesday night, said he had a plan to defy Democrats if he lost control of Congress. "I veto everything," he vowed.