Pat Wellenbach/AP Photo

Two candidates emerged victorious from a crowded field in Maine's Senate primary on Tuesday. Republicans nominated Charlie Summers, the Secretary of State, from a group of six potential candidates, and Democrats nominated Cynthia Dill, a state Senator from the South Portland area, from a group of four potential candidates.

But the frontrunner is generally considered to be Angus King, a former governor who is running as an Independent.

Republicans and Democrats have strong candidates in Summers and Dill. Summers, 52, is a commander in the U.S. Navy reserve who has served in Iraq and Afghanistan. He has served as secretary of state since 2011, and he served as the state director for Olympia Snowe, the retiring Republican senator whose seat he is looking to fill, for almost a decade. Snowe, however, has not yet committed to supporting her party's nominee.

Dill, 47, is a lawyer and self-described progressive Democrat. She has served in the Maine legislature since 2006, and in the state Senate since 2011.

It is King, 68, who is viewed as having the advantage in the race. The two-term governor who is independently wealthy enjoys a significantly higher name recognition in the state and stronger finances. King's record does not fall squarely in line with either party - he endorsed George W. Bush in 2000, backed Obama in 2008, and supported Independent candidate Eliot Cutler in Maine's gubernatorial race in 2010. But Maine is viewed as a more Democratic state, and therefore he is generally considered to be a more favorable candidate for Democrats.

Traditional Congressional protocol dictates that if King wins the election, he will have to choose a party to caucus with in the Senate, or he'd have to forgo good committee assignments. King has refused to say which party he'd align himself with, and he's even said that he's considering the option of giving up committee assignments to maintain his independence. That middle ground has left head-scratching in Washington, D.C.

Republicans have tried to tie King to the Democrats and paint Summers as a real Independent, while Democrats have remained largely silent on the race. The Democratic Senatorial Campaign Committee, which oversees Democratic Senate races, did not issue any statement congratulating Cynthia Dill on her victory like they usually do when a nominee emerges from a primary.

Although Maine is viewed as generally leaning towards Democrats, a Republican presidential candidate hasn't won the state since part-time Kennebunk resident George H.W. Bush in 1988. The governor, Paul LePage, is Republican, and the state's two senators, Susan Collins and Olympia Snowe, are Republican, although widely considered to be very moderate. And the state's two representatives in the House are Democrats.

Political independence is a point of pride in the state, and so it is likely that King will be able to make it through the Senate race without committing to either party, if he so chooses, which is sure to make for a very unique race.