A prosecutor made a surprising offer Friday to Mayor Kwame Kilpatrick: resign by Sept. 3 in exchange for the dismissal of one of two assault charges.

Doug Baker of the Michigan attorney general's office made the disclosure during a routine arraignment for Kilpatrick on the charges in one of two criminal cases against him.

Kilpatrick attorney Juan Mateo told Circuit Court Judge David Groner he had just learned of the deal offer and wasn't prepared to respond. Another defense attorney, James Thomas, said after the hearing: "We're preparing for trial."

A not guilty plea on the assault charges was entered on the mayor's behalf. Kilpatrick didn't speak in court.

The mayor is accused of shoving a sheriff's detective into another investigator while they tried to serve a subpoena on one of his friends July 24.

Kilpatrick is a superdelegate to the Democratic National Convention next week in Denver. Thomas said last week the mayor is interested in attending but conditions of his bond in the assault case prevent him from traveling outside the metro Detroit area.

A hearing was scheduled for Monday on Kilpatrick's bond conditions.

Separately, Kilpatrick and his former top aide, Christine Beatty, were charged in March with conspiracy, perjury, obstruction of justice and misconduct in office, mostly tied to their testimony in a civil trial. Sexually explicit text messages between the pair, published by the Detroit Free Press in January, contradict their sworn denials of an affair, a key point in the trial last year involving a former deputy police chief.

Meanwhile, Gov. Jennifer Granholm is scheduled on Sept. 3 to consider a request from the Detroit City Council to have Kilpatrick removed from office. Under Michigan law, a governor can remove an elected official for misconduct. That hearing could last several days.

Granholm declined Friday to discuss anything involving Kilpatrick.