In a motion filed Thursday with U.S. District Judge James Zagel, Blagojevich attorney Sam Adam says Obama has direct knowledge of allegations made in the indictment.
It would be extremely unusual for a sitting president to testify at a corruption trial.
A spokesman for the U.S. attorney's office, Randall Samborn, had no comment on the 11-page motion. The filing contained several sections blacked out, apparently because they refer to material that the court has placed under seal.
Blagojevich has pleaded not guilty to charges that accuse him of scheming to sell or trade the Senate seat left vacant by Obama's election as president.