Independent candidate Angus King on Tuesday won the Maine Senate seat being vacated by retiring Republican Olympia Snowe, effectively shifting the seat to the Democrats.

King, a former two-term governor, defeated Republican Secretary of State Charlie Summers and Democratic state Sen. Cynthia Dill in a closely watched three-way race that has big implications for control of the Senate.

King, 68, said he was inspired to run because Snowe described the Senate as broken. He cast himself as unbeholden to parties and able to broker compromise. He endured millions of dollars' worth of attack ads from Republican and conservative groups.

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King is expected to caucus as a Democrat, though he stopped short of saying so following his win Tuesday night.

"I’m going to go down to Washington early next week," King told Fox News. "I’ll have a chance to meet with the leadership in both parties. I’m going to talk to them about where I am, what I think and we’ll see where the best fit is."

"Frankly I want to be as independent as I can," he said. "I may have to join a caucus for one or two votes to organize the Senate, but I’m still going to call them as I see them. Nobody tells me how to vote except the people of Maine."

During his victory speech in Freeport, King spoke of what he called divisiveness within Congress and vowed to serve as a "bridge between my colleagues on both sides of the aisle."

"Maine is leading by saying that what we want is listening instead of lecturing, compromise instead of confrontation and solutions instead of slogans," King told a cheering crowd of supporters.

"My mandate is clear," he said. "To listen to the best solutions from every corner… and help my colleagues find common ground."

The race created unusual dynamics in which a GOP-led group spent heavily to prop up Dill in hopes of keeping Democratic votes away from King, a former Democrat. Later, the Democratic Senatorial Campaign Committee spent money to attack Summers after polls showed him gaining momentum against King.

King said the partisan gridlock that led Snowe to throw in the towel after 33 years in Congress was the reason he got into the race. He said he hoped to fix what he called a "broken" system. That having more independents elected to the Senate would be the major parties' "worst nightmare," he said.

The GOP was virtually assured of keeping the Senate seat before Snowe abruptly abandoned the race. Her announcement in late February, a week after her 65th birthday, caused a scramble. Summers, 53, of Scarborough, and Dill, 47, of Cape Elizabeth, won their crowded primaries.

Tuesday's ballot included two lesser-known independents, Tea Party activist and Libertarian Andrew Ian Dodge, of Harpswell, and former civil servant Danny Dalton, of Brunswick. Another independent, businessman Steve Woods, of Yarmouth, dropped out, but his name remained on the ballot.

Snowe, a self-described centrist who was attacked in her own party as a RINO, or "Republican in name only," didn't mince words as she prepared to exit the chamber.

She said she was weary of the pervasive "my way or the highway" views at both extremes of the political spectrum and lamented that the "sensible center has now virtually disappeared."

Snowe was using part of her re-election campaign fund to establish an organization aimed at encouraging young women to participate in public service. She opted not to spend any money this cycle on any candidates, including Summers, who declined to endorse her in her primary.

Fox News' Mary Quinn O'Connor and The Associated Press contributed to this report.