A former aide to Sen. Maria Cantwell is in federal custody after being arrested on a charge of attempting to sexually exploit a minor.

James Michael McHaney was fired Friday from his job as a scheduler for Cantwell, D-Wash., hours after he was arrested by FBI agents. The FBI said in a charging document that McHaney allegedly tried to set up a meeting with an undercover witness posing online as a teenage boy.

McHaney, who appeared in federal court Saturday, was being held without bond pending a court hearing Wednesday, said Channing Phillips, a spokesman for the U.S. attorney's office for the District of Columbia.

According to court papers, McHaney, known as Mike, tried to arrange a lunchtime meeting with an unidentified person posing as a 13-year-old boy. When the witness asked whether McHaney was interested in sex with a 13-year-old, McHaney allegedly replied, "I'll be there," the court papers said. He later asked for a photo of the child.

News of the arrest was first reported on The Smoking Gun Web site, www.thesmokinggun.com.

Congressional records show McHaney had worked as a scheduler in Cantwell's Washington, D.C., office since at least July 2006.

Cantwell's chief of staff, Michael Meehan, issued a statement Monday night saying McHaney had been fired.

"Late Friday afternoon the FBI informed our office that a Senate employee was arrested. The employee was immediately fired. Our office has and will continue to fully cooperate with the ongoing federal criminal investigation. Senator Cantwell has zero tolerance for crimes against children," Meehan said.

McHaney's lawyer, Thomas Abbenante, did not immediately return a telephone message seeking comment late Monday.