John Harris entered the plea in federal court this afternoon.
He had to re-enter the plea because prosecutors obtained a new indictment with similar charges.
He is accused of taking part in a conspiracy to sell or trade President Obama's former U.S. Senate seat
Harris has agreed to testify at Blagojevich's trial which is scheduled to begin on June 3.
In exchange, he will be sentenced to a maximum of 35 months in prison.