What's the matter with kids today? Dana Milbank, a grumpy old man at the Washington Post, would like to know. He's not literally talking about kids, but about voting age adults--the "army of 15 million voters under 30" who "swept [Barack] Obama past Hillary Clinton and John McCain and to the presidency in 2008," and the smaller force, "more than 12 million," who "helped him return in 2012."

"But now his presidency is on the line," Milbank warns, "and the Obama youth are...