She is the rare Republican who sometimes can boost her own popularity back home by keeping her distance from President Donald Trump, and she has perfected that delicate dance even as his tightening grip on the party has cost two of her Senate Republican colleagues their reelection.

Tuesday marked an especially significant moment for Graham Platner, the embattled veteran and oyster farmer, who is fighting to rebuild his credibility in a campaign rocked by controversy.

Republicans and Democrats in Nevada, North Dakota and South Carolina select their nominees on Tuesday, but much of the nation's political focus will be on Maine. Democrat Graham Platner is expected to emerge from the primary to take on five-term incumbent GOP Sen. Susan Collins. But Platner has faced one scandal after another during the campaign. Geoff Bennett discussed more with Alex Seitz-Wald.

Voters across Maine, Nevada, South Carolina and North Dakota head to the polls Tuesday for another day of primary elections in America, but much of the political world will be focused on Maine's high-stakes U.S. Senate contest.

Graham Platner is seeking to make a Democratic nomination for U.S. Senate official in advance of one of the most anticipated contests of the year.

Primaries for U.S. Senate and U.S. House on Tuesday will set the stage for a midterm general election in which Maine is expected to play a critical role in deciding control of both chambers.