A string of polls showing weak support for President Biden among younger Americans is serving as a warning sign for Democrats that Mr. Biden could be pushing these voters out of the party. Analysts, though, are skeptical that President Trump’s support on Election Day 2024 will see as strong as he sees in year-out polling.

An NBC News poll released over the weekend found that Mr. Biden trailed Mr. Trump by 4 points among voters aged 18 to 34. This was within the 6.2-point margin of error for that section of the poll, but still a far cry from Mr. Biden’s lead in 2020.

The NBC poll is an outlier among recent surveys, in that it shows Mr. Trump leading Mr. Biden among younger voters. Yet it is not an outlier in that it found that younger voters had swung toward Mr. Trump.

A New York Times and Siena College battleground poll, for one, found that Mr. Biden leads Mr. Trump by 1 point among voters aged 18 to 34 in select battleground states that will likely decide the 2024 presidential election.

Other polls, like a November Fox News poll, found Mr. Biden leading Mr. Trump by 7 points among voters aged 18 to 34. A November Quinnipiac poll came to a similar conclusion, showing Mr. Biden leading Mr. Trump by 9 points among voters aged 18 to 34.

The only recent survey that has found Mr. Biden leading Mr. Trump by a margin similar to his 2020 total is a CBS News poll that found Mr. Biden leading Mr. Trump by 25 points among voters aged 18 to 29.

In 2020, Mr. Biden won voters younger than 30 by 24 points and won voters younger than 50 by 12 points, according to a Pew Research analysis of election data.

NBC’s Mark Murray has tied a decline in support for Mr. Biden to his handling of the Israel-Hamas war. Mr. Biden’s approach to the issue is broadly unpopular, with 56 percent of Americans disapproving of his handling of the situation and 34 percent approving of his leadership on the issue, according to NBC’s poll.

This issue is even worse for Mr. Biden among younger voters, with 70 percent of voters aged 18 to 34 disapproving of his handling of the conflict.

Other analysts, like Michael Hais and Morley Winograd at the Brookings Institute, have suggested that broader disagreements with Mr. Biden on issues like climate change are driving his low support among younger voters, who are more likely than older voters to say they’re considering voting for a third party or independent candidate.

In a Brookings Institute Governance Studies survey, for one, voters aged 18 to 26 were twice as likely as voters aged 43 to 58 to say they thought Senator Manchin had a good chance of winning on the No Labels ticket, 8 percent to 4 percent, and nearly twice as likely to say it was possible for Mr. Manchin to win, 29 percent to 15 percent.

There are reasons to doubt that the statistical tie in support for Messrs. Trump and Biden among younger voters will hold through 2024.

A political scientist at John Jay College, Brian Arbour, tells the Sun that younger voters may, albeit reluctantly, support Mr. Biden over Mr. Trump as the nominating process wraps up and the election’s stakes become more present in the minds of voters, adding that the time at which the election becomes real for voters is “different for different people.”

“We’ve been aware that this is the most likely matchup for two or three years now,” Mr. Arbour tells the Sun. “That’s not true for everyone.”

Mr. Arbour also says that survey data a year out from the election is often unrepresentative of how voters will act on Election Day, adding, “With any poll there are sources of error and that’s heightened with younger voters.”

Mr. Arbour does, though, say, “It’s clear to me that Biden’s biggest issue is on enthusiasm,” and that political differences between Mr. Biden and younger voters could certainly play any into issues the president may have in getting people to the polls.

An associate editor at Sabato’s Crystal Ball at the Virginia Center for Politics, Miles Coleman, largely agrees with this assessment, saying, “Biden was never really the ‘natural’ candidate of younger voters,” adding that “it’s not a group that the Biden campaign can take for granted.”

Yet Mr. Coleman is also skeptical that most voters answering pollsters are paying as much attention to Mr. Trump and his campaign as they are to Mr. Biden.

“I think polls at this point are really just registering how grumpy people are about Biden,” Mr. Coleman says. “Next year, when the race will be seen as more of a choice between Biden and Trump rather than just a referendum on Biden, things will likely look worse for Trump.”