BREAKING NEWS: After days of quiet hand-wringing, a few Democrats went public with their concerns about the president, worried not only about his chances but also the party’s ability to hold the Senate and win the House.

Democratic anxiety over President Biden’s fitness to run for re-election erupted into the open on Tuesday in a spike of panic, as the first sitting member of Congress called on Mr. Biden to withdraw and a slew of other prominent officials who have backed the president vented their concerns.

One Democratic senator openly asked for assurances from the White House about Mr. Biden’s “condition” — “that this was a real anomaly and not just the way he is these days,” Senator Sheldon Whitehouse of Rhode Island told a local television station, where he said he had been “horrified” by the president’s debate performance.

Another, Senator Peter Welch of Vermont, scolded the Biden campaign for “a dismissive attitude towards people who are raising questions for discussion,” in an interview with Semafor.

And later on Tuesday, Representative Lloyd Doggett of Texas, a veteran progressive lawmaker, issued a statement saying that Mr. Biden’s debate performance, which he had hoped would give the president momentum to make up for his weakness relative to former President Donald J. Trump, had instead disqualified him from running again.
“I had hoped that the debate would provide some momentum to change that. It did not,” Mr. Doggett said. “Instead of reassuring voters, the president failed to effectively defend his many accomplishments and expose Trump’s many lies.”

The vast majority of Democrats, including party leaders, remain publicly supportive of Mr. Biden, and the few critics who have dared to voice their concerns so far are not major players in the party with large followings. Still, after days of privately fretting over Mr. Biden’s fumbling, faltering debate performance late last week, by Tuesday a growing number of Democrats appeared willing to air their frustrations.

It was a notable inflection point that came just a day after the president addressed the nation in prime time in an effort to assuage concerns about his ability to speak in public.

Distraught about the pressure from within Mr. Biden’s own firmament, White House officials were discussing sending Mr. Biden to battleground states, including to Wisconsin on Friday and Pennsylvania on Sunday, to do what allies have been urging: show him in public settings for longer durations. And they were discussing having Mr. Biden meet on Wednesday with Democratic governors, many of whom have not had direct contact with the president since the debate, causing exasperation among some who have yet to hear from him.

Much of the anxiety among lawmakers, strategists and operatives is being driven by a double-barreled fear — not just that Mr. Biden’s stumbles will cost him the White House, but that they might also make it impossible for Democrats to win the critical races that will decide control of the House and Senate, thus depriving them of a crucial check on the power of a potential Trump presidency.