Sen. Joe Lieberman says there should be a special counsel to look into allegations that the administration has leaked information on a U.S.-Israeli cyber-warfare campaign against Iran's nuclear program and other classified activities.
The Connecticut Independent also said President Barack Obama should instruct anybody on his staff involved in such leaks to come forward and that the president should himself be interviewed by investigators.
Both Democrats and Republicans have criticized apparent leaks about the cyber-warfare initiative, on Obama's selection of targets for counterterrorism assassination plots and the mission that killed Osama Bin Laden.
GOP critics have suggested the leaks were orchestrated to boost Obama's re-election bid.
Lieberman said a special counsel would avoid any appearance of conflict of interest.
Attorney General Eric Holder has appointed two U.S. attorneys to investigate.