By Nandita Bose and Trevor Hunnicutt
WESTON, Massachusetts/WASHINGTON (Reuters) -President Joe Biden said on Tuesday he may have skipped mounting a 2024 re-election bid if he were not facing Donald Trump because the Republican poses a unique threat to the United States.
"If Trump wasn't running, I'm not sure I'd be running," Biden said at a fundraising event for his 2024 campaign outside of Boston. "We cannot let him win."
Biden's striking self-assessment comes as even staunch Democratic voters express concerns about the president's age. The Democrat turned 81 years old last month and is already the eldest Oval Office occupant in history.
"Somebody gave him a talking point they thought would sound good," Trump, who was president from 2017 to 2021, said at a Fox News town hall on Tuesday.
Biden, seeking a second four-year term in next year's election, later told reporters at the White House that he would not drop out of the race.
"No, not now," Biden said when asked if he would consider stepping aside if Trump, 77, stopped seeking his own second term. "Look, he is running, and I have to run."
Asked if he would have run were Trump not in the race, Biden said, "I expect so."
During his 2020 presidential campaign, Biden often mentioned that his decision to run was due in part to then-President Trump's handling of issues, including a 2017 white nationalist rally in Charlottesville, Virginia.
Now, Biden faces limited competition for his party's nomination and is again positioning Trump as a danger to democracy itself.
Trump, who faces criminal charges over his efforts to reverse his 2020 election loss, has painted Biden as a dangerous autocrat.
After considering the decision for weeks with family and close confidants, Biden announced his re-election bid in April, coming to the private belief that neither Vice President Kamala Harris nor any other Democratic hopeful could beat Trump in next year's general election, according to a former White House official who requested anonymity to discuss the president's thinking.
The president's aides increasingly regard Trump's frontrunner status for the Republican presidential nomination as insurmountable, according to two of those Democrats who also declined to be named.
Biden has repeatedly made comments about Trump during a fundraising blitz that started on Tuesday in Boston and is set to include at least nine events before the end of the month.
"I don’t think anyone doubts our democracy is at risk again," Biden said earlier on Tuesday.
Recent polling has shown the Republican frontrunner leading Biden in hypothetical matchups in key swing states and on the national level.