President Barack Obama has an emerging slogan — “greater together” — that he’s using to spur support among younger voters worried about jobs, education and debt. The collectivist slogan is appearing in more places, including fundraisers and in the title of the “Greater Together Student Summit Tour,” which is sending Obama’s deputies to colleges to galvanize students and youth. On Feb. 1, Obama used the slogan to spur support among young and old African-Americans, and especially African-American women. Less than half of younger African-American men are in the workforce, and the average wealth of African-American families was slashed by the...