According to the plea agreement, Earl Krugel said he and Irv Rubin, the late leader of the militant group, discussed bombing Arab institutions in the Los Angeles area.
Krugel, 60, said they chose the Clemente office of Rep. Darrell Issa, R-Calif., because he was an Arab-American who "held political views contrary to their own."
Attorney General John Ashcroft said in a statement that the plea agreement makes clear that "acts of terror targeted at individuals because of their race, religion or national origin will not be tolerated in the United States."
Krugel faces 10 to 20 years in prison when sentenced May 19 on one count of conspiracy to violate the civil rights of the users of the King Fahd Mosque in Culver City and one count of carrying an explosive device in connection with a conspiracy to impede or injure an officer of the United States.
He could have faced a life sentence without possibility of parole if convicted at trial.
Krugel's attorney, Mark Werksman, said outside court that the deal was "distasteful," but his client "was going to basically die in prison if he went to trial and lost."
"We are facing a political climate where it's difficult to defend alleged actions of domestic terrorism," Werksman said.
Krugel and Rubin were arrested in 2001, after an FBI informant delivered an explosive powder to them.
Hours before they were to appear in court Nov. 4, Rubin slashed his neck with a prison-issued razor blade and tumbled 18 feet over a railing at the federal Metropolitan Detention Center, according to prison officials. He died nine days later.
Rubin's estate has filed a $5 million wrongful death claim against the government. His wife, Shelley, said Monday that she was shocked by the plea agreement and insisted her late husband had nothing to do with the bombing plot.
A JDL spokesman said Krugel had been dismissed from the group.
By Robert Jablon