President Barack Obama's political clout was on the line Tuesday as Virginia and New Jersey chose governors in contests that could serve as warning signs for Democrats about the public's mood heading into an important midterm election year. Elsewhere, Maine voters weighed in on same-sex marriage in a closely watched initiative, and New York and California picked congressmen for two vacant seats. A slew of cities selected mayors, and Ohio voted on allowing casinos. One year after Obama won the White House in an electoral landslide and Democrats expanded their majorities in Congress, much of the focus was on Virginia and New Jersey, where Democratic control was in danger despite hefty campaigning by Obama himself. The outcomes were sure to...