Former Vice President Joe Biden topped President Trump by 9 percentage points in a Fox News poll released on Saturday.
The likely Democratic nominee was backed by 49% of the survey's respondents in a theoretical matchup against Trump, who had 40% support. An additional 11% said they are undecided or will vote for someone else.
Last month, Biden had an 8-point lead over Trump, at 49% to 41%.
The former vice president in the new poll has a 9-point lead over Trump among voters who are extremely interested in the election, 52% to 43%. Biden also holds an 8-point advantage in battleground states, 48% to 40%.
But in counties where former Secretary of State Hillary Clinton and Trump were within 10 points of each other in 2016, Biden has a 25-point advantage, 57% to 32%.
When the theoretical matchup included Biden’s potential vice presidential candidate, only Sen. Elizabeth Warren (D-Mass.) tipped the Democratic ticket to majority support at 52%, compared to the Trump ticket at 42%.
Sen. Kamala Harris (D-Calif.) or Sen. Amy Klobuchar (D-Minn.) both push the Biden ticket to 50%, while Trump’s ticket stays at 42%.
Biden has committed to choosing a woman as his vice presidential candidate.
The Fox News poll of 1,011 randomly chosen registered voters was conducted between March 21 and 24. It has a margin of error of 3 percentage points.