WASHINGTON (AP) — Young voters who have been critical to Democratic successes in recent elections showed signs in November's midterms that their enthusiasm may be waning, a potential warning sign for a party that will need their strong backing heading into the 2024 presidential race.

Voters under 30 went 53% for Democratic House candidates compared with only 41% for Republican candidates nationwide, according to AP VoteCast, a sweeping national survey of the electorate. But that level of support for Democrats was down compared with 2020, when such voters supported President Joe Biden over his...