Sen. Martin Heinrich (D-N.M.) has endorsed Graham Platner in the Democratic primary for Senate in Maine. Platner, a Marine Corps veteran and oyster farmer, is running a populist campaign against five-term incumbent Sen. Susan Collins (R-Maine). His top competition is Maine Gov. Janet Mills (D), whom Senate Democratic Leader Chuck Schumer (N.Y.) is backing. In addition to Heinrich, Democratic Sen. Ruben Gallego (Ariz) and progressive Sen. Bernie Sanders are also backing Platner. In the past, numerous media outlets reported on offensive comments Platner made on Reddit, which he disavowed in October.