Joe Biden leads the Democratic field at 26%; Elizabeth Warren is at 17%

That nine-point margin is a decline from August, when he led by 18 points.

Among all voters, Trump narrowly edges an unnamed Democrat, 41%-39%.

WASHINGTON – Former Vice President Joe Biden continues to lead a turbulent field for the Democratic presidential nomination, a national USA TODAY/Suffolk University Poll finds, but his margin over Massachusetts Sen. Elizabeth Warren has been slashed in half. And most Democratic voters say they could still change their minds.

Almost exactly one year before Election Day – and 96 days before the opening Iowa caucuses – Biden was backed by 26% of likely Democratic primary and caucus voters in the survey. Warren was second at 17%, followed by Vermont Sen. Bernie Sanders at 13% and South Bend, Indiana, Mayor Pete Buttigieg at 10%.

Biden's lead over Warren, now 9 percentage points, was 18 points in the last USA TODAY/Suffolk Poll, taken in late August. His standing has fallen by 6 points since then; hers has risen by 3.

"My front-runner would be Biden," Nathaniel Dortch, 77, an Air Force retiree from Moreno Valley, California, who was among those surveyed, said in a follow-up interview. Then he added, "I want to wait and see."

Iowa caucuses: Poll shows they are 'up for grabs' as Buttigieg surges into top tier

In a sign of the prospect for changes ahead, 18% of likely Democratic voters were undecided. Among those with a preferred candidate, a 57% majority said their minds weren't firmly made up.

"I am undecided in supporting a specific candidate right now because I am not looking for the issue differential, I want someone best equipped to take on Donald Trump," said Freyr Thor, 56, a tech CEO from South Pasadena, California. He's worried about what he's seen, and hasn't seen, in the Democrats' televised debates so far. "No one has shown me they can take on Trump, including Biden."

Trump vs. any Dem: Who will win?

In a match-up between President Trump and an unnamed Democratic nominee, Trump narrowly led, 41%-39%, with 10% supporting an unnamed third-party candidate. Another 10% were undecided. That was a shift, albeit one within the margin of error, from the August survey, when the unnamed Democrat held a narrow lead over Trump, 41%-39%.

In the new poll, Republicans expressed overwhelming confidence about the outcome of the election, with 86% predicting the president would win. Seventy-five percent of Democrats said their nominee would win. But independents by a double-digit margin expected Trump to prevail.

Despite the cloud of impeachment, overall those surveyed predicted by 50%-40% that the president in the end would claim a second term.

"Trump has done a lot of the things he has set out to do," said John Siefkas, 52, a farmer and political independent from Osceola, Iowa, who was called in the poll. "He needs to keep his hands off Twitter, (but) he is doing some stuff that is needing done that people haven't had the guts to do."

William Collins, 56, an independent who is a retired police investigator from Fort Valley, Virginia, also plans to vote for the president. "I believe Trump has directed America in the right direction, and I think he really has the American people in his own heart."

Trump's job-approval rating was 46% approve-52% disapprove, with 27% saying they "strongly" approved and 37% saying they "strongly" disapproved.

More from the poll:Who's sticking with Trump? His seemingly unshakable base.

USA TODAY interview with David Rubenstein: 'The country will survive whatever happens now'

The telephone poll of 1,000 registered voters nationwide, taken Oct. 23-26, has a margin of error of plus or minus 3 percentage points. The sample of 399 likely Democratic voters has an error margin of 4.9 points; the sample of 323 likely Republican voters has an error margin of 5.5 points.

Large field helps Biden

Those surveyed were split down the middle when it comes to Congress: 43% said they supported the Democratic candidate in their district; 42% the Republican. Asked whether they would prefer Democrats or Republicans to win control of Congress next November, they divided 46%-46%.

The Democratic field now has a top tier of four candidates – Biden, Warren, Sanders and now Buttigieg, whose standing rose 4 points from the August poll. They were followed by Hawaii Rep. Tulsi Gabbard at 4% – up from less than 1% last time – and entrepreneur Andrew Yang at 3%.

California Sen. Kamala Harris was also at 3%, a drop of 3 points from August. Minnesota Sen. Amy Klobuchar, credited with a strong performance in the last debate, was at 2% – not a big number, but better than in August, when she registered no support. New Jersey Sen. Cory Booker also was at 2%.

None of the other 11 candidates had support higher than 1%, a troubling sign as they try to raise money and break through. Seven of them had either no or only a single backer in the survey.

"I like Warren, Harris and Booker," said Doleen Reynolds, 51, an independent from Slidell, Louisiana, who is concerned that Biden "would compromise too much" with progressive principles. "But if he gets the nomination, I will vote for him, because we cannot have the alternative."

The big field is helping Biden, said David Paleologos, director of the Suffolk Political Research Center. "Biden's strength has been, at best, fixed, and he benefits from so many other candidates splitting the non-Biden voters," Paleologos said. "Overall, Biden has led in the national polls for some time but you can't flatline to the Iowa caucuses."

Yearning for more candidates

The Democratic field has set records for size, but almost one in five Democrats, 18%, said they wished someone else would jump into the race. In response to an open-ended question about who, 10% identified former first lady Michelle Obama, 7% said former New York mayor Michael Bloomberg and 4% said Hillary Clinton, the party's 2016 nominee.

Among Republicans, a similar number, 17%, said they wished someone else would enter the GOP contest. Asked who, 8% said former UN ambassador Nikki Haley and 6% said Utah Sen. Mitt Romney, the 2012 nominee.

Mitt Romney: A solitary GOP voice battling Trump for the soul of the Republican Party

None of the three Republicans who are already running are cutting into Trump's support. In the poll, 85% of likely GOP voters backed Trump. Two percent supported former Massachusetts Gov. Bill Weld; and 1% each supported former South Carolina Gov. Mark Sanford and former Illinois Rep. Joe Walsh.

Who are the candidates? Meet them in our interactive guide