This was not a new way of delivering opposition research, but an official campaign event for Platner’s supporters. And it showed how the 41-year-old oyster farmer and military veteran has capitalized on voters’ willingness to forgive past transgressions and embrace a populist message. Platner is facing Governor Janet Mills, 78, in the June 9 primary, with the winner taking on five-term Republican Senator Susan Collins, 73, in a race that could help determine Senate control. “Graham Platner’s campaign gave me a place to put my energy in a positive way,” said Beth Knight, a 63-year-old teacher who attended the trivia...