The campaign of scandal-plagued Republican Rep. George Santos will lose its ability to raise donations or make payments if it fails to appoint a treasurer, the Federal Election Commission warned.
The FEC told Santos on Tuesday that it "has received no information regarding a new treasurer" since the former person in that role, Nancy Marks, resigned last month.
"It is required that for any committee to conduct any business, they must have an active treasurer," the FEC said in a letter to the New York lawmaker and his campaign committee.
"Failure to appoint a treasurer will result in the inability of the committee to accept contributions and make disbursements," the agency said. It added that campaigns are required to appoint a new treasurer within 10 days of the previous treasurer's resignation.
A lawyer for Santos did not immediately respond to CNBC's requests for comment.
Marks resigned as Santos' treasurer on Jan. 25, jumping ship in the midst of the freshman congressman's struggle to keep his head above a tidal wave of scrutiny surrounding his lies on the campaign trail and his finances.
That same day, the campaign filed an amended form listing Thomas Datwyler as its new treasurer. But Datwyler, through a lawyer, quickly denied that he had taken the job.
The FEC asked Santos' campaign for clarification, warning that "knowingly and willfully making any materially false, fictitious, or fraudulent statement or representation to a federal government agency" would lead to criminal charges.
In a year-end report filed Jan. 31, the Santos campaign listed as its treasurer a person named Andrew Olson.
No other information has been provided about Olson; his name does not appear as treasurer on any other committee reports that have been filed with the FEC. Olson has not yet filed a form that is required for him to become treasurer.
CNBC has so far been unable to make contact with Olson. Currently, the FEC lists Santos as his campaign's own treasurer.
"The way they filed it, Olson is not officially the treasurer," said Saurav Ghosh, the director of federal campaign finance reform for the Campaign Legal Center, in a recent phone interview with CNBC.
Ghosh said the "sloppiness" of the Santos campaign's year-end report suggests a lack of experience on the part of Olson, if he did indeed prepare it.
For instance, one individual made a $10,000 contribution to the campaign, which far exceeds the legal limit. "That's an obvious one," Ghosh said, and something that an experienced treasurer would have caught.
Santos has been bludgeoned with criticism and bipartisan calls to resign since shortly after winning his election to Congress, when a bombshell New York Times report questioned key details of his biography and the source of the money he used to help fund his campaign.
Santos later admitted lying about parts of his background, but he has denied committing any crimes and vowed to serve out his full two-year term in the House.
He has spent his first months in Congress weaving through throngs of reporters while mostly avoiding their questions about a wide range of damning allegations against him.
Santos is facing investigations at the local, state, federal and international level. The Department of Justice has reportedly asked the FEC to hold off on any enforcement actions against Santos while they conduct a criminal investigation into his campaign finances.
The FEC's latest notice adds to the pile of questions surrounding Santos' campaign conduct — including whether he plans to seek reelection.
Last week, the agency told Santos that his campaign committee's recent activity requires him to either declare himself a candidate for the 2024 election or disavow the campaign's moves, according to a letter obtained by CNN.
In a defiant tweet Tuesday, Santos asserted he's "not leaving, I'm not hiding and I am NOT backing down."