There's also at least one high-profile long-shot on the informal list being circulated inside Obama's camp: former Department of Homeland Security Secretary Janet Napolitano, who left Washington in 2013 to take over the massive University of California system, according to one Democrat with close ties to the White House.

Napolitano was the original choice for the job at the start of Obama's first term – a favorite of then-Chief of Staff Rahm Emanuel.

Holder, who had considered himself the sole front-runner for the job, was startled during the 2008-09 transition period when he was handed a Department of Justice binder that included headshots of himself and Napolitano as potential AGs.