The race for the U.S. Senate highlights Maine’s primary today, but the presumed frontrunner is not even on the ballot.

Voters are choosing among four Democratic candidates and six Republican candidates, all vying to face former Gov. Angus King, an independent who does not face a primary challenge. King is seen by many as the favorite because of the weaknesses of the major parties.

In 2010, Democrats lost both houses of the Maine legislature and the governor’s office, but Republicans suffered defeat in a 2011 special election as voters repealed a GOP-backed law that ended election-day voter registration.

That law was sponsored by Maine Secretary of State Charlie Summers, one of the leading candidates for the seat from which Republican Sen. Olympia Snowe is retiring.

The Waterville Morning Sentinel reported light voting so far, and that officials had predicted less than 20 percent turnout.

By Alex Remington, News21