Sen. Susan Collins, R-Maine, is followed by reporters as she leaves a meeting of Senate Republicans regarding the government shutdown and debt ceiling on Capitol Hill in Washington, Saturday, Oct. 12, 2013. (AP Photo/Charles Dharapak)
File: Sen. Susan Collins ( R-Maine) (AP Photo/Charles Dharapak)

Maine Sen. Angus King, a political independent who caucuses with the Democrats, is staying rooted in the political middle Friday by endorsing one of his Democratic colleagues and one of his Republican colleagues for reelection.

King is supporting Sen. Susan Collins (R-Maine) in her bid for reelection. He's also backing Sen. Jeanne Shaheen (D-N.H.).

"I think she's one of the Senate's MVPs — smart, tough, and always willing to listen. In my book, she's a model senator and I'm delighted to support her re-election," King said of Collins in a statement to the Associated Press.

Shaheen's campaign announced Friday that King would endorse her. Shaheen faces a potentially tough race since former Massachusetts senator Scott Brown (R) jumped in against her earlier this year.

King defeated Collins in a 1994 race for governor.

Collins is not expected to face much trouble in her campaign this year. The moderate Republican is broadly popular in Maine. Her Democratic opponent is Shenna Bellows, a former head of the American Civil Liberties Union.

Updated at 11:47 a.m. with the Shaheen endorsement