Grimm has been under investigation for campaign fraud by federal authorities for two years, and CNN reports that charges are expected to be filed on his former business dealings and alleged false statement.
"After more than two years of investigation plagued by malicious leaks, violations of grand jury secrecy, and strong-arm tactics, the U.S. Attorney’s Office has disclosed its intent to file criminal charges against Congressman Grimm," his lawyer, William McGinley, said in a statement.
"We are disappointed by the government's decision, but hardly surprised. From the beginning, the government has pursued a politically driven vendetta against Congressman Grimm and not an independent search for the truth."
Feds have been looking into Grimm's fundraising for his 2010 campaign for two years, and the former FBI agent made headlines in January after he threatened to throw NY1 reporter Michael Scotto off a balcony for asking about the probe.
In 2013, Ofer Biton, an associate of Grimm, pleaded guilty to visa fraud, the Daily News reported. Biton helped to raise up to $300,000 for Grimm's campaign from his Upper East Side congregation then illegally funneled money into his campaign, the News said.
And in January, a reported onetime girlfriend of Grimm's, Diana Durand, 47, was charged with election fraud and lying to agents for using straw donors to funnel into his campaign, the News said.
Grimm's lawyer said that the congressman "asserts his innocence" and will continue to serve Staten Island and Brooklyn.
"Congressman Grimm asserts his innocence of any wrongdoing," McGinley said. "When the dust settles, he will be vindicated."
Grimm is up for re-election and will face off against Democrat and former Brooklyn Councilman Dominic Recchia Jr.