June 9 (UPI) -- Five-Term Republican Sen. Susan Collins will soon learn who she will face in November as voters head to the polls in Maine's primary election on Tuesday. Voters in South Carolina, Nevada and North Dakota are also casting ballots in primaries with control of the U.S. House and Senate at stake. Collins' Senate seat is among those the Democratic Party believes it can flip and Tuesday's primary will determine the candidate that represents the party. Newcomer Graham Platner, former