The 2024 presidential election has set off a new wave of election denialism online — only this time, it is coming from voters on the left.

Much as many supporters of President-elect Donald J. Trump did after the 2020 election, some supporters of Vice President Kamala Harris are demanding recounts in key states in a bid to verify or even overturn the result. They are scrutinizing election results for signs of tampering, questioning whether election machines flipped votes and wondering whether digital technology could have injected fake votes.

“You know, I don’t agree with Trump on anything, except for this,” said Sandy Summers, a Harris supporter in Baltimore. “Like, yeah, don’t trust the machines. Why should we?”

Unlike 2020, though, the movement this year has nowhere near the organization or support of the Republican “Stop the Steal” campaign. Experts say that is largely because it doesn’t have an influential figurehead, like Mr. Trump was in 2020, to be its champion.

No one in the Democratic Party leadership has embraced the claims, which have been refuted by election officials. Representative Hakeem Jeffries, the House Democratic leader from New York, said in a statement after the election that he accepted the results and was “proud that the Democratic Party does not believe in election denial.” Ms. Harris has ignored pleas to challenge the result.

“It’s just clear that there’s a whole choir on the right that’s ready to sing,” said Bill Adair, professor of journalism at Duke University and founder of the fact-checking site PolitiFact, referring to supporters of Mr. Trump’s baseless claims. “And that just didn’t exist on the left.”