WASHINGTON, United States (AFP) — The top Republican in the US House of Representatives voiced confidence that his party will seize the lower chamber of Congress from President Joe Biden's Democrats after Tuesday's midterm elections.

House Minority Leader Kevin McCarthy, speaking to an election watch party in the early hours of Wednesday, struck a cautiously upbeat note as results showed Republicans were poised to flip the seats necessary to win control, albeit most likely with a smaller majority than experts had forecast.

"It is clear that we are going to take the House back," McCarthy said to raucous cheers.

"When you wake up tomorrow, we will be in the majority, and Nancy Pelosi will be in the minority," the lawmaker from California said, referring to the 82-year-old current speaker of the House who has been one of the most powerful leaders of the chamber in decades.

"The American people are ready for a majority that will offer a new direction, that will put America back on track," McCarthy said. "Republicans are ready to deliver it."

McCarthy and other conservatives had boasted of a likely "red wave" in the midterms that would topple Democratic control in both the House and Senate.

While control on Capitol Hill technically still hangs in the balance, early results suggested Republicans indeed were on track to take the 435-member House — but only by a handful of seats, a far cry from their predictions. The Senate remains a tossup.

A CBS News estimate overnight showed Republicans projected to win at least 202 seats and Democrats at least 188. A minimum of 218 seats is needed to win the majority.

McCarthy is the frontrunner to become the new speaker, a position he has coveted for years, particularly since his pathway to the speaker's gavel was derailed in 2015 when Paul Ryan won the top job instead.

He has said he believes his bid for speaker would have the support of former president Donald Trump.

McCarthy, 57, said in a CNN interview broadcast Monday that a Republican-led House would launch sweeping investigations of the Biden administration including on the US pullout from Afghanistan and the origins of the Covid-19 pandemic.