Zachares admitted engaging in official acts on Abramoff's behalf while working for Rep. Don Young, R-Alaska, who chaired the Transportation and Infrastructure Committee.
Abramoff assisted Zachares in obtaining his committee post. Zachares left Young's staff in 2005. Young's office did not return repeated phone calls seeking comment Monday and Tuesday.
Zachares pleaded guilty in front of U.S. District Judge Ellen Segal Huvelle to one count of conspiracy. He faces a maximum of five years in prison, but under federal sentencing guidelines will likely face two years or less.
He is the fifth congressional staffer to plead guilty in the Abramoff scandal, including two ex-aides to former House Majority Leader Tom DeLay, R-Texas.
Zachares entered his plea before Judge Ellen Segal Huvelle. He faces up to five years in prison, a fine of $250,000, and supervised release following his incarceration.