The top five Democratic presidential candidates all lead President Trump by significant, growing margins among registered voters and American adults a year before the 2020 election, according to a Washington Post/ABC News poll released Tuesday. Former Vice President Joe Biden, Sen. Elizabeth Warren (D-Mass.) and Sen. Bernie Sanders (I-Vt.) trounce Trump by 17 percentage points, 15 points, and 14 points, respectively, among registered voters.

New WaPo/ABC News 2020 match-up numbers pic.twitter.com/NTesrdAPVE — Morning Joe (@Morning_Joe) November 5, 2019

All Democrats included in the poll — Biden, Warren, Sanders, South Bend Mayor Pete Buttigieg, and Sen. Kamala Harris (D-Calif.) — have steadily improved their standing over Trump since July.

BREAKING: A year before the 2020 election, the top Democratic contenders extend their leads over Pres. Trump, new @ABC News/WaPo poll finds. https://t.co/5BfXoomGka pic.twitter.com/KXoZcGM8RP — ABC News (@ABC) November 5, 2019

Trump, hindered by a 39 percent approval rating, has lost most ground among independents, who account for most of the shift toward the Democratic candidates. Polls of the handful of swing states that will likely decide the election have shown a much tighter race, though if any Democrat actually beat Trump by double digits, they would almost certainly win both the popular vote and Electoral College. A year before the 2016 election, a Post/ABC News poll had Hillary Clinton leading Trump by 12 points among all adults but only by 3 points among registered voters, ABC News notes.

Trump is facing a slightly fractured Republican Party, the poll found: Only 80 percent of Republicans back him, while 16 percent of GOP-leaning voters say they would vote for Biden, and 30 percent of Republican and GOP-leaners say they wish the party would nominate someone other than Trump. But Democrats face their own fissures: Just over a third of 18- to 29-year-olds say they might sit out 2020 if Biden or Warren is the nominee, while 22 percent say the same of Sanders.

The Washington Post/ABC News poll was conducted by phone Oct. 27-30 among 1,003 adults, including 876 registered voters. The margin of sampling errors for all adults is ±3.5 percentage points and for registered voters, ±4 points. Peter Weber