A New York Times/Siena College poll revealed that even his supporters worry about his age. Among his supporters, 47% strongly believe that he is too old to be effective, and 26% somewhat agree.

The poll was conducted two weeks after a special counsel described Biden in a report as “well-meaning, elderly man with a poor memory and diminished faculties in advancing age.”

In six top battleground states, surveyed in October, 55% of those who voted for him in 2020 said that they believed he was too old to be an effective president, a sharp increase from the 16% of Democrats who shared that concern in 2020.

Voters have not expressed the same concern about Donald Trump who is four years junior to Biden. Biden will be 86 at the end of his second term.

Kamala Harris is not popular. Only 36% of all voters said they have a favorable view of her.

While Democrats are still divided, they seem to be slowly unifying behind Biden’s bid. 45% said that he should not be their nominee in a recent poll compared with 50% who expressed that view in July.

Overall, voters have a warmer view of Biden than Trump. 51% of registered voters said the president has the personality and temperament to be president, compared with 41 percent who said the same about Trump.

In the most recent Times/Siena poll, Biden lags Trump by 5%. Trump is supported by 48%. Biden is supported by 43%.

Only one in four voters thinks the country is moving in the right direction. More than twice as many voters believe Mr. Biden’s policies have personally hurt them as believe his policies have helped them. A majority of voters think the economy is in poor condition. And the share of voters who strongly disapprove of Mr. Biden’s handling of his job has reached 47 percent, higher than in Times/Siena polls at any point in his presidency.

The poll offers an array of warning signs for the president about weaknesses within the Democratic coalition, including among women, Black and Latino voters. So far, it is Mr. Trump who has better unified his party, even amid an ongoing primary contest.

Mr. Trump’s ability to consolidate the Republican base better than Mr. Biden has unified the base of his own party shows up starkly in the current thinking of 2020 voters. Mr. Trump is winning 97 percent of those who say they voted for him four years ago, and virtually none of his past supporters said they are casting a ballot for Mr. Biden. In contrast, Mr. Biden is winning only 83 percent of his 2020 voters, with 10 percent saying they now back Mr. Trump.