New Jersey state Sen. Barbara Buono has filed paperwork to challenge Gov. Chris Christie (R) in 2013, making her the first Democrat to officially join the race. 

The liberal Buono was ousted as Senate majority leader in late 2011 after repeatedly clashing with Senate President Stephen Sweeney (D), another potential Christie rival. She later lost her chairmanship of the Legislative Oversight Committee. 

To have a fighting chance, Buono will have to dramatically raise her profile in the state. In a recent Rutgers University poll, Buono trailed Christie 60 percent to 22 percent; a Public Policy Polling survey found a similar 40-point gap

Newark Mayor Cory Booker, considered the overwhelming favorite in a Democratic primary, has yet to announce whether he will run for the seat.