US President Joe Biden’s agenda hung in the balance on Tuesday on a tense election night, with one potential 2024 challenger, Ron DeSantis, winning a crushing victory for a new term as Florida’s governor.

As polls closed in the midterm elections, Republicans were projected to have picked up at least two seats in the House of Representatives but did not immediately show evidence of a major nationwide wave ahead of what is expected to be a long count.

With Republicans hammering Biden over stubbornly high inflation, his Democratic Party’s slender majorities in the House and Senate were on the line but the clearest early results were in the governors’ races.

Read more: US inflation hits new 40-year high

DeSantis, who has made a name in Florida by railing against Covid mitigation measures and transgender rights, was projected to have secured a landslide win of up to 20 points against a folksy former governor, four years after squeaking by in his longtime swing state.

“We will never, ever surrender to the woke mob,” DeSantis told a victory rally, using a derisive term for social justice campaigners.

“Florida is where woke goes to die,” he said.

But if the 44-year-old views his victory as a mandate for the White House in 2024, he will likely face a stiff challenge from another Florida resident — Donald Trump.

The former president went to the polls teasing an announcement next week of a potential new White House run, telling reporters that November 15 “will be a very exciting day for a lot of people.”

“I think if he runs, he could hurt himself very badly,” Trump separately told Fox News, of DeSantis.

Among other gubernatorial races, two solidly Democratic states, Massachusetts and Maryland, elected Democrats to succeed popular moderate Republican incumbents.

And the incoming leader of Massachusetts, Maura Healey, will make history as the first openly lesbian governor in the United States.

Trump again alleges fraud

Trump, who is facing criminal probes over taking top secret documents from the White House and trying to overturn the 2020 election, has returned to his playbook of airing unsubstantiated claims of fraud.

In Arizona, expected to be one of the closest states, Trump and his chosen candidate for governor, Kari Lake, alleged irregularities after problems with voting machines.

“I hope it’s not malice,” Lake told reporters. “When we win, there’s going to be a come-to-Jesus for elections in Arizona.”

Officials in Maricopa County, which includes the Phoenix metropolis, said about 20 per cent of the 223 polling stations experienced difficulties related to printers but that no one was denied the right to vote.

A judge denied a Republican bid to keep the polls open later.

Biden has warned that Republicans pose a dire threat to democracy with more than half their candidates repeating Trump’s debunked claims of cheating in the 2020 election.

In his final pitch, Biden vowed that the Democrats would defend pensions, health care and the freedom to have an abortion, after a Supreme Court transformed by Trump rescinded the right to choose.

“It’s all on the ballot. This election is too important to sit out,” Biden tweeted in a last-minute bid to drive voters to the polls.

The president’s party has traditionally lost seats in midterm elections and Biden’s favorability ratings are hovering in the low 40s.

Narrow margins

All eyes are on a handful of closely fought Senate races including in Georgia, Pennsylvania, Nevada, Arizona, Wisconsin and Ohio, with a single seat enough to swing control of the Senate — now evenly divided and controlled by Democrats only through the tie-breaking vote of Vice President Kamala Harris.

The outcome may also determine whether Biden, who turns 80 this month and is the oldest president ever, will seek a second term in 2024.

Voting in Phoenix, Kenneth Bellows, a 32-year-old law student, said runaway inflation is “hurting Americans who are just trying to get by”.

“We don’t need any of the crazy woke rhetoric that’s going on right now. What we really need is focusing on everyday kitchen-table politics, to make sure taxes are low,” he said.

But at a restaurant serving up soul food in Pittsburgh, Lasaine Latimore, 77, said that Democrats were the best placed to help people.

“I just want my medical insurance and more money for dental and glasses,” she said.

If both the House and Senate flip, Biden’s legislative agenda would be paralysed as Republicans launch aggressive investigations and oppose his spending plans.

That would raise questions over everything from climate policies, which the president will be laying out at the COP27 conference in Egypt this week, to Ukraine, where some Republicans are reluctant to maintain the current rate of US military support.

The campaign was marred by scattered violence with an intruder espousing far-right beliefs breaking into the San Francisco home of House Speaker Nancy Pelosi and bludgeoning her husband with a hammer.

Pelosi said the Democrats hoped to prevail but would accept any election outcome.

Election Day is “a day where the sanctity of the vote is revered, where people vote, and we have to respect the results of that,” Pelosi told the PBS Newshour.