The leading progressive acknowledged Platner's controversial past statements in an interview with HuffPost. WASHINGTON ― Sen. Elizabeth Warren (D-Mass.) endorsed Graham Platner in the competitive Maine Democratic primary to decide who will take on Republican Sen. Susan Collins in November. Warren’s endorsement is a significant boost for Platner, whose chief rival in the crowded Democratic primary, Gov. Janet Mills, has the full backing of party leadership. In a video statement posted by Platner’