Sen. Bernie Sanders plans to join Democratic presidential nominee Hillary Clinton this week at an event in New Hampshire where they will pitch a joint plan to make college more affordable -- part of a continuing effort to sell the party’s ticket to wary millennials. Sanders, the runner-up in the Democratic primaries, consistently outperformed Clinton among young voters. As he prepared to exit the race in July, he worked with Clinton to incorporate parts of his college plan into hers. The result is a proposal to make public colleges and universities tuition-free for families with income up to $125,000 a...