Another Trump-picked candidate, former football star Herschel Walker, was forced into a 6 December runoff in his Georgia race against Democratic US Senator Raphael Warnock. That has raised some concerns that Trump's announcement could again hurt the party's chances in a Georgia runoff, similar to the January 2021 runoff that gave Democrats their current majority.

Multiple Trump-aligned candidates who ran on platforms focused on his false claims of widespread election fraud were also defeated.

While control of the House of Representatives is still undecided, the "red wave" that Republicans expected to carry them to a wide majority did not materialize despite Democratic President Joe Biden's low public-approval ratings. Voter anger over a Supreme Court decision to end national abortion rights offset concerns over high inflation.

"This should have been a huge red wave ... and yet we still didn't perform," said Maryland Governor Larry Hogan, a moderate Republican who has toyed with the idea of launching his own White House run.

"It's the third election in a row that Donald Trump has cost us the race ... I'm tired of losing," he told CNN on Sunday.

A Reuters/Ipsos poll taken before the election showed that 53 per cent of Americans and almost one in four Republicans view Trump unfavorably. The poll showed a similar number of Americans viewing Biden unfavorably.

Trump plans to launch his campaign nearly two years before the 5 November, 2024, election despite these concerns, said two sources familiar with his plans.

"President Donald J Trump and his team are firing on all cylinders and fully focused on saving our country," said one source, who spoke on condition of anonymity.

DeSantis, who Trump has given the derisive nickname "Ron DeSanctimonious," handily won re-election during the midterms. Pence is releasing a book on Tuesday detailing Trump's unsuccessful pressure campaign to overturn his 2020 defeat.

Legal Troubles

Trump will seek his party's nomination even as he faces trouble on several fronts, including a criminal investigation into the removal of classified documents from the White House as well as a congressional subpoena related to his role in the 6 January, 2021, US Capitol attack by his supporters. Trump has called the various investigations he faces politically motivated and denies wrongdoing.

The businessman-turned-politician, who has sought to maintain an iron grip on the Republican Party since leaving office, has persisted in making false claims the 2020 election he lost to Biden was stolen through widespread voting fraud.

Trump is seeking to become only the second US president in history to serve non-consecutive terms, after Grover Cleveland, whose second stint ended in 1897. Biden, 79, has said he intends to run for re-election to a second four-year term in office, though he has yet to make a final decision.

During his turbulent 2017-2021 presidency, Trump defied democratic norms and promoted "America First" nationalism while presenting himself as a right-wing populist. He became the first US president to be impeached twice, though congressional Democrats failed in their attempts to remove him from office.

At a rally that preceded the Capitol attack, Trump urged supporters to "fight like hell" and march on Congress to "stop the steal," but the mob that subsequently stormed the Capitol failed to prevent Congress from formally certifying Biden's election victory. Five people died in the riot.

Even though court and state election officials rejected Trump's false election claims, about two-thirds of Republican voters believe Biden's victory was illegitimate, according to Reuters/Ipsos polling.