(CNN) Former Vice President Joe Biden leads President Donald Trump in a hypothetical head-to-head matchup in Wisconsin, according to a Marquette University Law School poll released on Wednesday.

Biden is up over Trump by 51% to 42% among registered voters in Wisconsin. The President also trails Sen. Bernie Sanders of Vermont, who tops Trump 48% to 44%, just barely outside the margin of error.

Trump is tied against Sens. Elizabeth Warren of Massachusetts (45% each) and Kamala Harris of California (44% each).

Numbers this far out from a general election are hard to read, and could change between now and November 2020. They should be thought of as a snapshot in time rather than a predictor of the future.

Among the Democratic candidates, Biden leads the pack with 28% of registered Democrats, Democratic-leaning independents and independents who don't lean toward either party saying he was their first choice, followed by 20% for Sanders and 17% for Warren. Sanders beat out former Secretary of State Hillary Clinton in the 2016 Wisconsin Democratic primary, 57% to 43%.

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