Washington: US President Donald Trump trails at least three Democratic hopefuls - Joe Biden, Bernie Sanders and Elizabeth Warren - in theoretical head-to-head match-ups for the 2020 general election, a new poll showed.

Democratic presidential candidate Senator Elizabeth Warren. Credit:AP

Biden, the former vice president, held the biggest lead among registered voters in the NBC News/Wall Street Journal poll released Sunday: 51 per cent to 42 per cent, well outside the survey's margin of error, which was plus or minus 3.5 percentage points.

Senator Sanders of Vermont led Trump by 50 per cent to 43 per cent, and Senator Warren of Massachusetts was up 48 per cent to 43 per cent. A fourth Democrat, Senator Kamala Harris of California, was up against Trump by a point, 45 per cent to 44 per cent.

Biden's larger lead over Trump was largely due to his stronger performance among independent voters, white people and suburban residents than the rest of the Democratic field.