Democratic advertising blitz awaits Donald Trump

Long before Donald Trump swatted away his Republican presidential rivals, his likely Democratic opponent and her allies began laying traps for him. Priorities USA, the lead super PAC backing Hillary Clinton, has already reserved $91 million in television advertising that will start next month and continue through Election Day. In addition, Clinton’s campaign and Priorities USA have both debuted online videos that cast Trump in a negative light — a preview of what voters will see on TV over the next six…