Sen. Elizabeth Warren said Thursday she’s backing political newcomer Graham Platner in the Democratic primary for U.S. Senate. Warren, a prominent progressive from Massachusetts and 2020 Democratic presidential contender, said she thinks Platner is the best candidate to take on five-term Republican incumbent Susan Collins in November. “Graham Platner is going to flip Maine and then actually deliver change for working people in the Senate,” Warren said in a written statement. Warren is ramping up her efforts to elect progressives in this year’s midterm elections. In January, she donated a combined $400,000 to 23 state party committees, including Maine’s, Politico...