The defining moment of Donald Trump‘s Friday night campaign rally in Mobile, Ala. was when the GOP candidate for president called Jeff Sessions onto the stage. The four-term U.S. senator put on one of Trump’s trademark “MAKE AMERICA GREAT AGAIN” hats. Sessions may well be the Senate’s most unrepentant racist. He was once nominated for a federal judgeship, but his history of racism — including praising the KKK and calling the Voting Rights Act “intrusive” — tanked his nomination. Trump isn’t supposed to be a serious candidate, and an endorsement from a U.S. senator is a huge step for him....