WASHINGTON — Joe Biden is running stronger against President Donald Trump in hypothetical general election matchups in Pennsylvania and other key states than his top rivals for the Democratic nomination, according to a new poll.

While Sen. Elizabeth Warren of Massachusetts has surged nationally, Sen. Bernie Sanders of Vermont retains a fervent base of support, and Biden has faced questions about enthusiasm for his candidacy, the survey of Pennsylvania and five other battleground states suggests that the former vice president has the upper hand in the places that could ultimately decide the 2020 election.

In theoretical head-to-head match ups in Pennsylvania, the New York Times and Siena College poll released Monday found:

  • Biden leads Trump by 3 percentage points among registered voters, 47-44

  • Warren trails Trump by 1 percentage point, 44-45

  • Sanders leads Trump by 1 percentage point, 45-44

The differences between the Democrats aren’t huge, but could be significant when it comes to the Electoral College — and thus the outcome in 2020. Trump lost the popular vote in 2016, but won the presidency on the back of razor-thin victories in Pennsylvania, Michigan, and Wisconsin. Tiny swings in those states could again determine the winner.

While Trump’s national approval rating is stuck in negative territory, the poll suggests he has retained his standing among the key demographic that powered him in 2016. Among white voters without college degrees, Trump’s lead over Biden, Warren, and Sanders matched or nearly matched the 26 percentage-point advantage he enjoyed over Clinton, an edge that proved crucial in Rust Belt states such as Pennsylvania.

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The poll of 3,766 voters in six states included 661 in Pennsylvania. It had a margin of error of 4.4 percentage points in the Keystone State — enough that it could erase the differences between the Democratic candidates’ performances. The poll, of course, is one snapshot in a race that will continue evolving, and it comes before Democrats have even cast their first votes.

However, the results across all six swing states were consistent: The poll found Biden running stronger against Trump than either Sanders or Warren. Along with Pennsylvania, the Times and Siena also polled Arizona, Florida, Michigan, North Carolina, and Wisconsin.

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The findings come one year before Election Day and with less than 100 days until Democrats will formally begin to choose their nominee in the Iowa caucuses. The poll also lands as Democrats increasingly argue over whether they should aim to win back moderate swing voters to unseat Trump, as Biden contends, or campaign with bold, dramatic strokes to excite progressives, as Warren and Sanders have done.

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In Pennsylvania, some of the key differences between the two top Democrats come down to support among African Americans. Biden wins support from 91% of black voters in Pennsylvania, compared to 78% for Warren and 75% for Sanders, the poll found.

More broadly, a small, but potentially significant, sliver of voters would support Biden but not Warren across all six battleground states polled. Many of them said they would prefer a moderate nominee to a liberal one, and they also held more conservative views on cultural issues.