Former Gov. Angus King has won the Senate race in Maine, running as an independent. King will take over the seat held by retiring Republican Sen. Olympia Snowe.

King has said he will be a bridge between the parties and hasn't said which party he will caucus with, but Republican groups have spent millions of dollars opposing him and he is expected to align with the Democrats.

Democrats now control the Senate 53-47, including two independents who caucus with them: Vermont's Sen. Bernie Sanders, who also has been re-elected, and retiring independent Sen. Joe Lieberman of Connecticut.

Four Democrats senators have also won re-election: Bill Nelson in Florida, Sheldon Whitehouse in Rhode Island, Ben Cardin in Maryland and Tom Carper in Delaware. Republican Sen. Bob Corker was re-elected in Tennessee.