Lt. Governor Eleni Kounalakis made the announcement after California Secretary of State Shirley Weber certified the recall effort.
Newsom, a Democrat, is only the second sitting governor in California history to face a recall election. Gov. Gray Davis was successfully recalled in 2003 and replaced by Arnold Schwarzenegger.
Newsom signed a law earlier this week to speed up the recall process. Critics objected to the move, alleging Newsom and his allies are trying to rush the election while conditions are favorable.
This is a breaking story and will be updated.