The liberal former candidate's backing of the centrist Nunn, who's running for retiring Sen. Saxby ChamblissSaxby ChamblissSpicer: Trump will 'help the team' if needed in Georgia special election Wyden hammers CIA chief over Senate spying Cruz is a liability MORE's (R-Ga.) seat, is the latest sign top Democrats are lining up to support her candidacy. Dean is a lobbyist at the law and lobbying firm, as is Gordon Giffin, Nunn's top advisor and a longtime Georgia Democratic strategist.

Democrats are hopeful that Nunn can give the GOP a tough race in the red-leaning state.