New York Congressman Michael Grimm, who represents parts of Staten Island and Brooklyn, pleaded not guilty to tax evasion charges and posted $400,000 bail.

The U.S. attorney unsealed a 20-count indictment against Rep. Grimm related to his former restaurant, Healthalicious. Officials say he avoided paying taxes by employing undocumented workers and paying them off the books and then lying to investigators about it. The alleged fraud went on from 2007 until 2010. Investigators say he under-reported over $1 million of his restaurant's sales and wages.

The indictment also includes charges of mail fraud and wire fraud, each of which carry a maximum penalty of 20 years in prison.

"Since day one, the press has been fed all type of innuendo and accusations to support a political witch hunt. And this political witch hunt was designed to do a couple of things but first and foremost assassinate my character and remove me from office," said Rep. Grimm.

Grimm's attorney released a statement saying in part, "From the beginning, the government has pursued a politically driven vendetta against Congressman Grimm and not an independent search for the truth." He added that the representative maintains his innocence and will be vindicated.