The Democratic National Committee filed a Federal Election Commisison complaint against Robert F. Kennedy Jr.’s presidential campaign on Friday, alleging illegal coordination with an outside group supporting his White House bid.

In a letter to the FEC, the DNC wrote that the group backing Kennedy, American Values 2024, “has begun making, and Team Kennedy accepting, in-kind contributions to assist Robert F. Kennedy Jr.’s candidacy in violation of federal law.”

The complaint specifically alleges that the group has illegally contributed to Kennedy Jr.’s signature-gathering efforts, which are necessary for Kennedy to qualify for several state’s presidential ballots as an independent candidate.

“Mr. Kennedy has stated that his goal is to appear on the ballot in all 50 states and DC,” the DNC wrote. “Mr. Kennedy and his campaign have also stated that this process is challenging and expensive. Rather than solving this problem by raising the necessary funds consistent with federal law, Mr. Kennedy and his campaign are trying to take the short cut of having American Values 2024 perform this campaign function for him.”

Registered as a hybrid PAC, with the ability to solicit unlimited contributions, American Values 2024 is prohibited from coordinating directly with Kennedy’s presidential campaign. But the complaint argues that coordination is required for the ballot access efforts by American Values and Team Kennedy, and thereby the group’s support runs afoul of campaign finance laws.

In a social media post on Friday, Kennedy pushed back on the DNC’s accusations.

“The DNC is accusing my campaign of FEC violations in the form of secretive activity—activity that’s so secretive it’s on the Ballot Access HQ of my website,” Kennedy wrote on X. “After the day they had yesterday, it’s understandable they’d want to put the focus on someone else.”

“The DNC is in no position to assert morality over anyone—they refused to have a primary and have worked against the will of the people in the past few elections. It’s sad to see the party my family built crash and burn,” he continued.

Kennedy campaign manager Amaryllis Fox Kennedy denied coordinating with the outside group in a statement to CNN.

“To my knowledge, we have yet to receive any signatures from American Values PAC or any PAC, nor have we provided any information that is not available to every volunteer and media outlet on our public website,” she said. “I am aware that they have their own signature collection tracker on their public website, but we take our FEC obligation seriously and are not permitted to tell PACs what they should and should not do with their money.”

American Values co-Chair Tony Lyons said in a statement to CNN the PAC’s ballot access operation has complied with FEC laws and labeled the filing as a “desperate DNC tactic.”

“American Values 2024 has been working independently from the campaign in accordance with FEC precedent to get Bobby Kennedy on the ballot in 12 states,” Lyons said in the statement. “The DNC wants to deny millions of people their basic constitutional voting rights in a relentless onslaught against democracy.”

In December, American Values announced plans to gather signatures on behalf of Kennedy in 10 states, targeting states where additional support to the campaign may be useful based on the number of signatures needed to qualify and the complexity of the state’s election laws.

“We have chosen to pursue these critical states, some of them battlegrounds, due to the complexity of the state election codes and the volume of signatures necessary to achieve ballot access. A successful ballot access initiative ensures Robert F. Kennedy, Jr as an option for president of the United States,” Deirdre Goldfarb, a ballot access attorney for American Values 2024, said in a statement announcing the signature gathering initiative in December.

Earlier this month, the PAC announced plans to gather signatures in an additional four states, and said signature gathering has already begun in Michigan, Arizona and Georgia.

In the complaint, the DNC alleges the PAC “must coordinate” with the Kennedy campaign to successfully operate its supplemental signature gathering operation.

“Put simply, to qualify for the ballot under state law, American Values 2024 must coordinate its activity with Mr. Kennedy and his campaign in a way that violates federal campaign finance laws,” the DNC wrote.

In a call with reporters outlining the complaint, DNC officials tied American Values’ signature gathering operation to former President Donald Trump and said supporters of Trump are donating to the Kennedy-aligned PAC to prop him up as a “stalking horse,” specifically singling out donations from Republican megadonor Tim Mellon.

“What we’re witnessing with this scheme is the outsized illegal influence of individual mega donors like billionaire Tim Mellon, Donald Trump’s largest donor this cycle, who gave American Values the exact $15 million paycheck they said that they would need for ballot access,” DNC adviser Lis Smith told reporters on Friday. “This is an effort to subvert our election laws and prop up a stalking horse in RFK, Jr. We have no choice but to file a complaint.”

Mellon, heir to a historic family banking fortune, gave about $15 million to American Values 2024 last year. He has also been a prolific donor to pro-Trump and other GOP causes over the years. In 2020, he gave $20 million to America First Action Inc., one of the lead outside groups supporting Trump’s reelection, and he’s given tens of millions more to other top GOP super PACs since 2018.

“We’re concerned that Donald Trump is disrespecting the democratic process. It’s pretty clear that Trump and his mega donors are propping up RFK Jr. as a stalking horse,” DNC adviser Ramsey Reid said.