A Democratic super PAC said it is filing a formal complaint with the Federal Election Commission on Monday accusing Donald J. Trump of violating campaign finance law by spending political funds on a 2024 presidential bid without formally declaring himself a candidate.

The complaint uses Mr. Trump’s own words about a 2024 run — “I know what I’m going to do, but we’re not supposed to be talking about it yet from the standpoint of campaign finance laws,” he said in the fall — to accuse him of improperly using his existing political committees to advance a presidential run.

Federal rules require those who raise or spend more than $5,000 in support of a presidential campaign to register with the Federal Election Commission.

Mr. Trump has repeatedly teased that he plans to run for president again, saying at the Conservative Political Action Conference last month, “We did it twice and we’ll do it again.” But though he formally filed for re-election the day of his inauguration in 2017, Mr. Trump has not done so for 2024. Such a filing would set off restrictions on how he could raise and spend campaign money, including his existing war chest.

Trump-controlled committees entered 2022 with $122 million in the bank — far more than the Republican Party itself.

“He should have to adhere to the law in a way that all other candidates do,” said Jessica Floyd, the president of American Bridge, the Democratic group that is filing the complaint. “When he says ‘I’m going to do it a third time,’ that’s not flirting. That’s more than a toe dip.”

Ms. Floyd noted that Mr. Trump’s citations of campaign law show clear intentions to evade the existing rules. “It’s not like he doesn’t know what he’s doing,” she said.

Taylor Budowich, a spokesman for Mr. Trump, called the complaint frivolous.

“America is spiraling into disaster because of the Democrats’ failures, and instead of reversing course, they are busy filing frivolous complaints that have zero merit,” he said.

Mr. Trump told the Fox News host Sean Hannity in July 2021 that he had made up his mind about another White House bid. A month later, he said on Fox News again that it was “unbelievably stupid” campaign finance laws that prevented him from directly stating his intentions.

“Let me put it this way: I think you’ll be happy, and I think that a lot of our friends will be very happy. But I’m not actually allowed to answer it,” Mr. Trump said then. “It makes it very difficult if I do.”

Nothing legally bars Mr. Trump from declaring he is running for president. But he would be subject to additional fund-raising limits and disclosure requirements if he did so.

Once a politician has decided to run for federal office and begun fund-raising, the person is supposed to file paperwork declaring the candidacy. There is also an interim step for those who are “testing the waters” of a run.

The American Bridge complaint says Mr. Trump has crossed both thresholds, though the line is notoriously blurry.

For now, Mr. Trump’s main PAC, called Save America, is registered as a committee that can spend on behalf of others, and the PAC did give away $350,000 to other candidates in 2021, though that sum is far less than the amount the PAC has spent on Mr. Trump’s own properties.

The complaint would appear unlikely to generate any crackdown by the Federal Election Commission, which is equally divided between commissioners aligned with the Democratic and Republican parties, and often deadlocks on contentious matters. The watchdog agency’s investigations process is also notoriously slow. A complaint to the commission related to the pre-candidacy activities of Jeb Bush, who announced his run for president in 2015, was still in court as recently as December 2021.