George Santos announced he will not run for re-election in 2024, after the House ethics committee released a damning report on his conduct.
The panel found the congressman “blatantly stole from his campaign” and exploited “every aspect of his House candidacy for his own personal financial profit”.
Mr Santos on social media called the report a “politicized smear”.
Still, he said he would not seek a second term in light of the probe.
“My family deserves better than to be under the gun from the press all the time,” he wrote in a long post that also called the report biased.
The New York Republican’s time in office could end sooner than next November, though.
Two of his congressional colleagues said on Thursday they would introduce measures to expel him from the House.
In its report, the ethics committee – which is split evenly between Republicans and Democrats – found that Mr Santos reported fictitious loans to his political committees in order to induce donors to make further contributions to his campaign.
He then diverted campaign money to himself as “repayments” of those fictitious loans, it found.
“He used his connections to high value donors and other political campaigns to obtain additional funds for himself through fraudulent or otherwise questionable business dealings,” the committee said in a report. “And he sustained all of this through a constant series of lies to his constituents, donors, and staff about his background and experience.”
He also allegedly charged expenses, such as thousands of dollars of Botox treatments and a stay at an Atlantic City resort, that did not have a clear connection to his campaign.
The ethics committee said it would not start disciplinary action itself because the process would provide the congressman “with further opportunity to delay any accountability for his actions and could risk interfering with the ongoing criminal prosecution”.
It added, though, that his “conduct warrants public condemnation, is beneath the dignity of the office, and has brought severe discredit upon the House”.
They referred Representative Santos to the Department of Justice for possible prosecution on additional charges.
Mr Santos has already been indicted on charges including conspiracy, wire fraud, false statements, falsification of records, identity theft and credit card fraud.
After the report was released Thursday, the chair of the ethics committee, Mississippi Republican Michael Guest, said he would personally introduce a measure to expel Mr Santos from Congress, Fox News reported.
Another lawmaker, California Democrat Robert Garcia, also said in an online post that he would introduce an expulsion measure.
Earlier this month, Santos survived a vote to expel him from the House, which a requires two-thirds majority.
Only five federal lawmakers have been expelled in US history, including three during the nation’s civil war.