Joe Biden said Thursday that President Trump will try to delay the November election, or put in place policies that make voting highly burdensome, in order to win a second term in the White House. The comments, made during a virtual fundraiser, represent the former vice president’s most explicit warning about the potential for an unprecedented power grab by the president in November.

Trump does not have the power to postpone the election and has not suggested that he’ll do so. But the extraordinary remarks from Biden, the presumptive Democratic nominee for president, highlight the disruption of norms that have taken place in the Trump era, and the impact that the novel coronavirus is having on the fabric of American lives.

“It’s perfectly appropriate for the vice president to speculate about that,” said Steve Schmidt, a Republican consultant who has long been skeptical of Trump. “We’ve had elections through the Civil War, world war, the Great Depression, assassinations, but we’ve never had an election where Donald Trump is the incumbent president of the United States and behind in the polls.”

“When you look at Trump at the podium speculating about shooting up Lysol or drinking bleach to deal with the virus, anybody who thinks that he wouldn’t speculate about that is mistaken,” he added.

Biden didn’t mince words on Thursday. “Mark my words, I think he is going to try to kick back the election somehow, come up with some rationale why it can’t be held,” Biden told a group of donors.

It’s not the first time he’s focused on the issue.

In previous interviews and fundraisers, Biden has stressed that the country cannot postpone the November election. Last week, when asked whether he believes the public can trust that the November election will be held as expected, Biden replied, “Right now they can’t trust that.”

The White House declined to comment on whether Trump is considering a delay or exploring any ways to do so. Tim Murtaugh, the communications director for the Trump campaign, did not directly respond to an inquiry about whether Trump might seek a postponement but disparaged Biden for making the comments.

“Those are the incoherent, conspiracy theory ramblings of a lost candidate who is out of touch with reality,” Murtaugh said in a statement.

Mike Reed, a spokesman for the Republican National Committee, said there are no plans to try to alter the date of the general election. “The answer to your questions is no,” Reed said in an email.

But Biden’s comments echo fears percolating among many Democrats. During the primary election, voters sometimes quizzed candidates on what they would do if Trump refused to leave office after losing.

“I just think there are a lot of people asking a lot of questions,” said Rep. Debbie Dingell (D-Mich.) “And the American people want their Democracy to continue the way that it always has and for there to be an election in November. And that election will probably mean more to them than many have.”

Focusing on this deeply ingrained concern among Democrats might be an effort by Biden keep his base engaged, said Amy Walter, national editor of the nonpartisan Cook Political Report.

“The president has his bully pulpit every day to keep his base engaged and they are as supportive of him as they’ve ever been,” Walter said. “Biden does not have that opportunity. Being in your basement in Wilmington is not exactly the best place to unify and energize your party.”

Compounding concern among Democrats is that many health experts believe the virus will return in the fall, making voting particularly challenging. Fifty-eight percent of voters support changing laws so everyone has the option to cast a ballot via the Postal Service, according to an NBC News-Wall Street Journal poll released last weekend.

But Trump has opposed policies that would make voting more accessible during a pandemic, including urging states not to adopt vote by mail procedure. And the NBC-Wall Street Journal survey showed a massive partisan divide: 82 percent of Democrats and 61 percent of independents favored allowing everyone to vote by mail, but only 31 percent of Republicans favored that policy.

Rather than focusing on whether Trump might delay the election, Biden should lay out a plan for November, said Bill Kristol, the director of Defending Democracy Together, a political nonprofit founded by Republicans focused defending democratic norms.

“He would do better advised to say, ‘We need to have a safe and secure election,’ ” Kristol said. “ ‘And we need to spend the money on it now. We need to alter some rules state by state to make that possible.’ ”

“It’s much better to say it that way than to sort of accuse Trump of some conspiracy.”

Asked to clarify his remarks, Biden spokesman Bill Russo focused on the recent Wisconsin primary, where voters had to wait in crowded polling places, despite the risk that they could contract the virus.

“What Wisconsin voters were forced to endure because of the chaos around their election cannot happen again,” Russo said in a statement. “This is exactly why we have to start grappling with these issues in a real way now, before the fall. There is huge urgency on this.”

Democrats also have pointed to more recent developments, like the Trump administration’s recommendation that the Postal Service adopt a new pricing model and charge market-rate prices on letters and packages.

Voting experts also worry polling locations will be drastically reduced in November if the virus returns and election workers become scarce.

On Thursday night, Biden also focused on Trump’s ideas to overhaul the Postal Service.

“Imagine threatening not to fund the post office,” Biden said Thursday night. “Now what in God’s name is that about? Other than trying to let the word out that he’s going to do all he can to make it very hard for people to vote. That’s the only way he thinks he can possibly win.”

Scott Clement contributed to this report.