Maine Gov. Paul LePage is a conservative Republican, and the two senators, Snowe and Susan Collins, are moderate, even sometimes labeled as RINOs (Republican in Name Only.) The state's two congressional representatives - Chellie Pingree and Mike Michaud - are Democrats. Pingree is considered to be much further to the left, while Michaud is a member of the Blue Dog Coalition of moderate Democrats.
King is challenged in the race by two candidates: Secretary of State Charlie Summers, the Republican nominee, and state Sen. Cynthia Dill, the Democratic nominee.
Dill and Summers are more cut-and-dry party candidates. Dill, 47, is a self-described progressive Democrat and former trial lawyer who represents the heavily Democratic area of South Portland in the state Senate. Summers, 52, is an Iraq war veteran who once served as state director for Snowe. Summers also served as a state senator in a traditionally Democratic district in the southern part of the state.
Both candidates only recently claimed their respective party's nominations, beating out a crowded primary field, and their operations are really just beginning to grow. Dill has four full-time staffers. Summers has six, although his staff expects that number to double in coming weeks. While the two candidates differ on many policy issues, they have a common enemy in the race: King.
"Angus, he was governor for eight years. Five of those years were incredible economic times and anybody could have been governor and gotten high marks because all he did was figure out how much money there was to spend," Summers told ABC News during an interview at the Motor Speedway in Scarborough. "The fact is that he doubled state spending and left a billion and a half dollar hole for a friend of mine, John Baldacci."
Baldacci is the Democratic predecessor to Republican Gov. LePage.
Summers has the backing of the National Republican Senatorial Committee as well as the state's Republican party, but Dill is backed only by the Maine State Democratic party. National Democrats have largely stayed out of the race.
That is because despite his independent affiliation, King is widely considered to be much more Democrat-friendly than Republican-friendly. He endorsed Barack Obama in 2008 and again this election. He endorsed Sen. John Kerry for president in 2004, but he endorsed George W. Bush in 2000.
Many of his positions are more Democratic in nature: he is pro-abortion rights, supports the Affordable Care Act and is against the Citizens United Supreme Court ruling that opened the flood gates to campaign contributions. But he holds some Republican friendly beliefs as well, such as favoring the reduction of some financial regulations.
Democrats believe that King will ultimately be on their side in the Senate, so national Democrats are staying away, despite Dill's presence as a true blue candidate.
"It's really Democrats who are fighting for working families and small businesses and trying to address the biggest problems that we have, which are huge disparities in incomes and wealth and money influencing the Democratic process" Dill said.
"It's really important that people know that the last time this country was in good fiscal shape, it was under a Democratic administration."
King says he has not yet decided what he will do if elected.