“It was a good day, I think, for democracy,” Biden told reporters at the White House on Wednesday.

White House officials have expressed a sense of vindication that Democrats did better than expected after Biden focused his campaign pitch largely on preventing threats to US democracy, securing abortion rights and extolling his economic policies.

Republicans made modest gains in US midterm elections and are likely to take control of the House of Representatives but control of the Senate hinges on three races that remained too close to call on Wednesday afternoon.

Biden said he was prepared to work with Republicans.

“The American people have made clear, I think, that they expect Republicans be prepared to work with me as well,” he said.

Biden said he would veto efforts to pass a national ban on abortion and opposed tax cuts for the wealthy, two policy proposals Republicans might pursue.

He said when he returns from a trip to Asia he will invite Democratic and Republican leaders to the White House to discuss priorities going forward.

Biden said he expects to decide early next year whether he will seek re-election for another four-year term.

He repeated that he intends to run for office again but that it was a family decision and he would seek their consultation over the holidays.

“I am a great respecter of fate,” Biden told reporters.

Two thirds of midterm voters – including 43 per cent of Democrats – would prefer that Biden not seek re-election in 2024, according to exit polling conducted by Edison Research.

Ninety percent of Republican voters do not think he should run, the poll found.

While final results in several races were not in yet, Democrats may have held onto control of the Senate and have narrowed expected losses in the House, bucking historical trends for the party of a new president.

“President Biden will and should run for re-election and he’ll win,” Democratic strategist Jennifer Holdsworth told Reuters.

“He has led a tremendously successful administration and the American people recognise that.

“Republicans and pundits alike continue to underestimate him at their own peril.”

Another Democratic strategist, Karen Finney, said the midterm result should mean Biden “gets all the time he wants to decide” on what to do about 2024.

Biden may have to do some convincing to get voters to warm to the idea.

The White House had crafted a message casting Republicans as extremists planning to take away women’s rights and defund popular social programs, even as some pundits suggested focusing more on the economy.

Some strategists were also crediting Vice President Kamala Harris for her campaign work and pushing the message of reproductive rights despite harsh criticism of the strategy.

Even a slim majority in the House of Representatives would let Republicans hem in Democratic Biden during his next two years in office, blocking legislation and launching potentially politically damaging investigations.

But they appeared to be far short of the sweeping “red wave” victory they had sought, as Democrats were avoiding the kind of heavy midterms defeat that often plagues sitting presidents of either party.

Control of the Senate remained unclear, as Democrats picked up a seat in Pennsylvania but awaited results from Nevada, Georgia and Arizona that would define the outcome. Another competitive race broke in Republicans’ favour, as Edison Research projected that incumbent Senator Ron Johnson would win re-election in Wisconsin.

The results appeared to show voters punishing Biden for presiding over an economy hit by steep inflation, while also lashing out against Republican efforts to ban abortion.

Poor performances by some candidates backed by Donald Trump indicated exhaustion with the kind of chaos fomented by the former Republican president, raising questions about the viability of his possible run for the White House in 2024.

“I think his ego is just too big to handle,” said Yvonne Langdon, 75, as she cast her ballot for Republican candidates in Michigan on Tuesday.

Biden had framed Tuesday’s election as a test of US democracy at a time when hundreds of Republican candidates embraced Trump’s false claims that the 2020 presidential election was stolen from him.

A number of election deniers who backed Trump’s claims were elected to office on Tuesday, but fears of violence or other major disruptions by far-right poll watchers at voting stations did not materialise.

By early Wednesday, Republicans had flipped a net six Democratic House seats, Edison Research projected, one more than the minimum they need to take over the chamber. That number could go up or down as more final results roll in.

Control of the Senate would give Republicans the power to block Biden’s nominees for judicial and administrative posts. But in a critical win for Democrats, John Fetterman flipped a Republican-held US Senate seat in Pennsylvania, beating retired celebrity surgeon Mehmet Oz and bolstering his party’s chances of holding the chamber.

The Georgia race appeared to be headed for a runoff vote on December 6 because both the Democratic and Republican candidates were falling short of the 50 per cent needed for victory.

The White House seized on the lighter-than-expected losses. “Never underestimate how much Team Biden is underestimated,” White House Chief of Staff Ron Klain said on Twitter.

But Democrats also had their share of embarrassments, as New York Representative Sean Patrick Maloney, the chairman of the committee charged with re-electing House Democrats, conceded he had lost his own race.

If the Republicans do take control of Congress, they plan to seek cost savings in the Social Security and Medicare safety-net programs and make permanent tax cuts enacted in 2017 that are due to expire.

Republicans also could engineer a showdown over the debt ceiling to extract major spending cuts, and could pare back aid to Ukraine.

The party that occupies the White House almost always loses seats in elections midway through a president’s first four-year term, and Biden has struggled with low public approval.

Trump, who took an active role in recruiting Republican candidates for Congress, had mixed results.

He notched a victory in Ohio, where “Hillbilly Elegy” author JD Vance won a Senate seat to keep it in Republican hands. But Oz lost his Pennsylvania Senate race and Doug Mastriano, another Trump ally, was handily defeated in the state’s governor’s race.

Trump allies also were struggling in Arizona, Georgia and Nevada Senate races, where ballots were still being counted.