Public-opinion polls are a snapshot in time, and results can change quickly in politics as events intrude. But the polls have been sending Democrats and President Biden the same election warning for months, so perhaps they’ll eventually start listening.

The latest Siena College-New York Times poll of six battleground states, released on the weekend, is a five-alarm fire for Democrats a year before the election. It shows Mr. Biden losing to Donald Trump in five of six states on which the 2024 election is likely to hang.