The loss takes away some of Biden's power in Washington but on Wednesday he congratulated McCarthy and said he would work across the aisle to deliver results.

"The American people want us to get things done for them," Biden said in a statement.

House Speaker Nancy Pelosi said in a statement House Democrats "will continue to play a leading role in supporting President Biden’s agenda - with strong leverage over a scant Republican majority."

Democrats have been buoyed by voters' repudiation of a string of far-right Republican candidates, most of them allies of Trump, including Mehmet Oz and Doug Mastriano in Pennsylvania's Senate and governor's races respectively, and Blake Masters in Arizona's Senate contest.

Even though the expected "red wave" of House Republicans never reached shore, conservatives are sticking to their agenda.

In retaliation for two impeachment efforts by Democrats against Trump, they are gearing up to investigate Biden administration officials and the president's son Hunter's past business dealings with China and other countries - and even Biden himself.

On the international front, Republicans could seek to tamp down US military and economic aid to Ukraine as it battles Russian forces.

The tug of inflation and abortion

The United States returns to its pre-2021 power-sharing in Washington, with voters tugged in opposite directions by two main issues during the midterm election campaigns.

High inflation gave Republicans ammunition for attacking liberals, who won trillions of dollars in new spending during the COVID-19 pandemic. With voters seeing their monthly grocery, gasoline and rent bills rising, so rose the desire for punishing Democrats in the White House and Congress.

At the same time, there was a tug to the left after the Supreme Court's June ruling ending the right to abortion enraged a wide swath of voters, bolstering Democratic candidates.

Edison Research, in exit polls, found that nearly one-third of voters said inflation topped their concerns. For one-quarter of voters, abortion was the primary concern and 61 per cent opposed the high-court decision in Roe v. Wade.

In the Los Angeles mayoral contest, Edison projected that Democrat Karen Bass, a top progressive in Congress, had defeated Rick Caruso, a billionaire former Republican who ran on a platform of reducing crime and homelessness in the city. She stood at 53 per cent of the vote so far.

Eyes on the presidential race

While the midterms were all about elections for the US Congress, state governors, and other local offices, hovering over it all was the 2024 US presidential race.

Trump, who still polls as the top choice among Republicans for the party's presidential nomination, nevertheless suffered a series of setbacks as far-right candidates he either recruited or became allied with performed poorly on Nov. 8. Some conservative Republican voters voiced fatigue with Trump.

At the same time, Ron DeSantis coasted to a second term as governor of Florida, defeating Democratic opponent Charlie Crist by nearly 20 percentage points. Trump reportedly was seething over the high marks political pundits were doling out to DeSantis, seen as a potential challenger to Trump in the 2024 field of Republican presidential candidates.

The 2024 election will immediately influence many of the legislative decisions House Republicans pursue as they flex their muscles with a new-found majority, however narrow.

They have publicly talked about seeking cost savings in the Social Security and Medicare safety-net programs and making permanent 2017-enacted tax cuts that are due to expire.

Conservatives are threatening to hold back on a needed debt-limit increase next year unless significant spending reductions are achieved.

"It's critical that we're prepared to use the leverage we have," far-right House Freedom Caucus Chairman Scott Perry told Reuters last month.

First, the House must elect a speaker for the next two years. McCarthy on Tuesday won the support of a majority of his caucus to run for the powerful position to succeed Pelosi.

With such a narrow majority, McCarthy was working to get commitments from nearly every member of his unruly Republican members, having failed in just such an endeavor during a 2015 bid. Freedom Caucus members, about four dozen in all, could hold the keys to his winning the speakership and the viability of his speakership writ large.