Federal prosecutors are readying criminal charges against Rep. Michael Grimm (R-N.Y.) following a two-year FBI investigation into alleged misuse of campaign funds and improper business dealings by the congressman.

The New York Republican is a top Democratic target too, and the impending indictment further complicates GOP efforts to hold onto the Staten Island-based swing district. 

Grimm’s attorney, William McGinley, confirmed the proceedings in a statement, which said the congressman “asserts his innocence of any wrongdoing” He added that “we are disappointed by the government’s decision, but hardly surprised" saying they had "pursued a politically driven vendetta against" Grimm "and not an independent search for the truth."

“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,” McGinley said.

“When the dust settles, he will be vindicated. Until then, he will continue to serve his constituents with the same dedication and tenacity that has characterized his lifetime of public service as a Member of Congress, Marine Corps combat veteran, and decorated FBI Special Agent,” McGinley concluded.

Grimm has been under investigation for a range of allegations surrounding his business dealings and campaign finances, and drew increased scrutiny after a donor and close friend of the congressman was charged with funneling illegal contributions to Grimm's campaign.

He also sparked negative headlines earlier this year after he was caught on tape threatening to throw a reporter over a balcony in a House office building after the reporter asked about the ongoing investigations.

But the upcoming charges against the congressman are expected to surround Grimm’s previous business dealings and, according to CNN, “alleged false statements he provided to the government” about them.

The federal investigation has also focused on Grimm’s relationship with Ofer Biton, a donor who pleaded guilty last year to falsifying documents for a visa application. Biton helped Grimm raise more than half a million in donations, some of which were allegedly improper.

CNN is reporting that the charges could be filed as early as next week.

First elected in 2010, Grimm is a top Democratic target this cycle, partly because of the investigations he's been facing. He represents a swing district that went for President Obama in 2012, a year that Grimm won reelection by just 5 points.

Democrats have touted New York City Councilman Domenic Recchia as a top recruit, and he's banked over $1 million for the contest. Grimm, who spent $50,000 of campaign funds on legal fees the first two months of 2014, has nearly $1.2 million on hand but also has over $450,000 in debt. 

—Russell Berman contributed reporting. 

This post was updated at 7:45 p.m.