Several Biden aides and advisers, speaking on condition of anonymity, gave their assessment of how the president and his team view Trump's entry into the race. Trump made his announcement on Tuesday night as he sought to get a jump on potential rivals for the Republican nomination.

Biden, who defeated Trump in the contentious 2020 election, thus far is remaining mum publicly. When he and French President Emmanuel Macron were asked by reporters at the G20 meeting in Bali if they had a reaction to Trump's announcement, they looked at each other briefly and shared a faint smile.

"Not really," Biden said, before turning his attention back to the mangrove trees he and other world leaders were planting.

His aides described Trump as a vulnerable and defeated figure who motivates Democratic voters to go to the polls and reminds centrists of the chaos and turmoil that surrounded his presidency. They also portrayed Trump as a threat to U.S. democracy through his continued false assertion that the 2020 election was stolen from him through widespread voting fraud - a claim that motivated the Jan. 6, 2021, attack on the U.S. Capitol by his supporters.

"Trump is definitely the most vulnerable of the candidates but he does come with a cost the White House is keenly aware of," said a top Democrat who works with the White House on political issues, speaking on condition of anonymity.

It is important not to underestimate Trump nor his influence on Republican leaders, another Biden adviser said, noting that Trump has been written off many times in the past by pundits only to re-emerge stronger.

Biden, who already is the oldest U.S. president and turns 80 on Sunday, has not formally announced whether he will seek re-election. Trump is 76. Most Americans would like 75 as the cutoff age for running for president, according to Reuters/Ipsos polling.

Senior Biden aides including Anita Dunn have started sketching out staffing and organizational plans for Biden's expected re-election campaign, according to a person briefed on the plans. The expectation is the campaign would be staffed and ready for an early 2023 announcement from Biden and fully functional by the spring, that person said.

'VERY FORTUNATE'

Biden in March was asked by reporters gathered in Brussels for an emergency meeting on Ukraine whether he would like to run again against Trump. Biden responded, "In the next election, I'd be very fortunate if I had that same man running against me."

Biden defeated Trump by more than 7 million in the nationwide popular vote tally and by a margin of 306 to 232 in the state-by-state Electoral College that determines the outcome of presidential elections.

Trump made his announcement a week after U.S. congressional elections in which his party under-performed expectations. Several Trump-backed candidates lost midterm House and Senate races and those who echoed his false claims about the 2020 election were defeated in key contests.

Republicans are still pointing fingers over who was to blame for the party's lackluster performance, with some blaming the Trump influence. But the businessman-turned-politician remains the top choice of Republican voters for the 2024 race in opinion polls.

Trump's team appears hopeful about the opportunity of a rematch with Biden.

"We are pretty giddy about Biden running," a Trump adviser told Reuters, speaking on condition of anonymity.

Biden has said he will finalize a decision on whether to run after holiday consultations at the end of the year. During a news conference after the midterms, Biden suggested there would be little change from the themes that animated his 2020 campaign: restoring the soul of the country by purging Trump-like rhetoric, building the economy from the middle out and bottom up, and uniting the country.

A few hours before Trump's announcement, the White House launched a new webpage highlighting the Biden administration's achievements from creating manufacturing jobs and lowering drug prices for seniors to gun reform.

Whether Trump is able to secure his party's 2024 nomination depends upon a number of factors including who are his opponents - Florida Governor Ron DeSantis is considered a major potential rival - and whether party leaders, donors and influencers decide to stay by his side.

Fifty-six percent of voters in the midterms had an unfavorable view of Biden and 41% viewed him favorably, according to an exit poll conducted by Edison Research, while 58% had an unfavorable view of Trump and 39% viewed him favorably. In addition, more than two-thirds described U.S. democracy as "threatened" rather than "secure." A third held the view that Biden was not elected legitimately.