Former Vice President Joseph R. Biden holds an 8-point lead over President Trump in a hypothetical match-up in Ohio, according to a poll released Thursday.
Mr. Biden led Mr. Trump, 50% to 42%, according to the Quinnipiac University poll.
Conversely, Mr. Trump either held a narrow lead or was tied in match-ups against Sen. Bernard Sanders of Vermont, Sen. Elizabeth Warren of Massachusetts, Sen. Kamala D. Harris of California, Mayor Pete Buttigieg of South Bend, Indiana, and Sen. Cory A. Booker.
Mr. Biden also led the way in the race for the Democratic nomination, with 31% support from Democrats and Democratic-leaning independents.
Ms. Harris and Mr. Sanders were next at 14% apiece, followed by Ms. Warren at 13% and Mr. Buttigieg at 6%.
Eight candidates were at 1%, including Mr. Booker and native son Rep. Tim Ryan.
“Former Vice President Joseph Biden calls himself a blue-collar guy. With Ohio certainly a blue-collar state, it is no surprise he is the Democrat who runs best against President Donald Trump and is solidly ahead in the Democratic primary in the Buckeye State,” said Peter Brown, assistant director of the Quinnipiac University Poll.
Mr. Trump carried Ohio in 2016 by about 8 points, after President Barack Obama had won the state in 2008 and 2012.
“Biden runs best against President Trump in every Quinnipiac University state poll so far,” Mr. Brown said. “To get reelected, Trump will need to win the industrial Midwest. Ohio certainly is key to that plan.”
The survey of 1,431 Ohio voters was taken from July 17-22 and has a margin of error of plus or minus 3.2 percentage points.
The subsample of 556 Democrats and Democratic-leaning independents has a margin of error of plus or minus 5.1 percentage points.