Philadelphia Mayor Jim Kenney said Wednesday that the city is preparing for the possibility that supporters of President Donald Trump will try to intimidate voters on Election Day, after Trump falsely singled out in Tuesday night’s debate it as rife with voter fraud, and reiterated a call to supporters to monitor polling places in the overwhelmingly Democratic city.

“Based on his comments, we’re going to be making an inter-agency plan for that day,” Kenney told The Inquirer on Wednesday.

Kenney said the city welcomes official poll watchers, who must be certified by the state and sponsored by a campaign or political party. But he added that if Trump’s comments lead to uncertified monitors intervening at polling places, police may need to stop them.

“People are simply not allowed to stand around there and intimidate people,” Kenney said.

While the city needs to plan for the worst case, Kenney said, he doesn’t expect there to be significant disruption.

“I don’t want to make too much of a big deal out of this, because a lot of these things never pan out,” Kenney said.

Trump closed out his first presidential debate with Democratic nominee Joe Biden on Tuesday night by repeating on national television his false claim that poll watchers had been blocked from observing the first day of in-person early voting in Philadelphia.

“Today there was a big problem,” Trump said. “In Philadelphia they went in to watch. They’re called poll watchers. A very safe, very nice thing. They were thrown out. They weren’t allowed to watch. You know why? Because bad things happen in Philadelphia, bad things.”

“I’m urging my supporters to go into the polls and watch very carefully, because that’s what has to happen,” Trump also said.

But the Trump campaign has no poll watchers approved to work in Philadelphia at the moment. And there are no polling places open in the city now, just satellite elections offices for requesting and submitting mail ballots. Poll watchers don’t have the same rights at such locations as they do at traditional polling places on Election Day.

Trump’s focus on Philadelphia is part of an effort by the president to sow doubt about the legitimacy of the election and specifically, mail ballots, which Trump has falsely attacked as susceptible to widespread fraud. His relentless campaign against mail voting has discouraged Republican voters from using the method, and both polling and data on mail ballot requests suggest Biden supporters will be voting by mail in far greater numbers.

Voting rights advocates fear the president will seek to disqualify or slow down the counting of mail ballots in swing states like Pennsylvania that could decide the election. Trump stoked those fears Tuesday by again refusing to commit to accepting the election results.

“If I see tens of thousands of ballots being manipulated, I can’t go along with that,” he said.

Philadelphia officials on Wednesday echoed their remarks from 2016, when Trump also baselessly claimed voter fraud in Philadelphia could “steal the election.” Both Democratic and Republican officials scrambled to defend the integrity of the election that year, and there were no reports of significant fraud.

“He said the same things in 2016, we had a fair election then, and we will have a fair election now,” said Lisa Deeley, a Democrat who chairs the city commissioners, who run elections.

Republican City Commissioner Al Schmidt responded Tuesday night by tweeting a photo of the U.S. Constitution. “Good things happen in Philadelphia,” Schmidt wrote.

At least one woman claiming to be a Trump campaign poll watcher was barred from entering one of the satellite offices Tuesday in the Overbrook section of West Philadelphia. The Trump campaign didn’t respond to questions Wednesday, but forwarded a copy of a letter it sent to the city commissioners on Tuesday that threatened legal action if the commissioners did not allow the campaign’s unofficial poll watchers in the satellite offices.

“No one questions that Philadelphians are voting at these locations,” Trump campaign lawyer Linda A. Kerns wrote. “The entire debacle that played out in Philadelphia today should concern everyone who promotes election integrity.”

State Rep. Martina White (R., Phila.) said it’s appropriate to ask questions about who is working at the satellite offices, and to question why observers are not permitted.

“People deserve to know what’s going on at these sites and that they have the right to question their government,” she said. “Both parties should want to be able to observe what goes on at these satellite locations. It’s not a political issue. It really is an election integrity issue.”

But Secretary of the Commonwealth Kathy Boockvar, the state’s top elections official, said Trump’s characterization of what happened Tuesday in Philadelphia was “completely inaccurate.”

“First of all, there are no poll watchers yet," she said. “Those are officially appointed a few days before the election and they literally don’t exist right now.”

U.S. Sen. Pat Toomey (R., Pa.) did not directly address Trump’s claims or his call for supporters to “go into the polls and watch very carefully.” Instead, he criticized a September ruling by the Pennsylvania Supreme Court allowing mail ballots to be counted if they arrive by the Friday after Election Day — even if their postmarks are missing or illegible.

That ruling “could heighten instances of voter fraud,” Toomey said. “Moreover, it’s possible that this decision will lead to a lengthy, disputed, and controversial outcome in what is expected to be an extremely close presidential race."

U.S. Rep. Brendan Boyle (D., Phila.) said he was concerned even before Tuesday’s debate that Trump would “make Philadelphia the poster boy” for his unfounded claims of widespread fraud.

“We have a dangerous person sitting in the Oval Office,” he said. “I never imagined I would have this conversation about an election in the United States of America.”

Both Toomey and Boyle called for lawmakers in Harrisburg to prevent delayed and disputed election results by allowing mail ballots to be counted before Nov. 3 — but Toomey added a caveat that only ballots received by Election Day should be counted. Legislative negotiations appeared stalled after the Supreme Court ruling.

Bob Brady, chair of the Democratic City Committee, said Trump is attacking Philadelphia because he knows he can’t win over the city’s voters.

“The reason why they complain so much is because they can’t beat us. But we don’t cheat,” Brady said. “We’ve been threatened before with intimidation. All that does is make us madder; all that does is get us more energized. So I thank him for last night, and also the fact that he mentioned Philadelphia. That was nice of him.”

Republican City Councilmember David Oh said Philadelphia shouldn’t be a focus for concerns about voter fraud.

“I’m not aware of any wholesale voter fraud,” he said. “That doesn’t mean you shouldn’t be concerned and prepared, but I haven’t seen things that would evidence a need to be concerned about Philadelphia more than any other place in the country.”

U.S. Rep. Dwight Evans (D., Phila.) said Philadelphians would not stand for Trump’s “gangster-style intimidation.”

“He can say all that he wants, but that would not be accepted in the neighborhoods I’m from,” he said.

-Staff writer Chris Brennan contributed to this article.