The Atlantic's Marc Ambinder writes,
The Republican wins in New Jersey and Virginia and the close race in New York City tells us...
...self-financers, people affiliated with Big Wall Street, the Old Money Crowd, the establishment, the party leadership... are being put on notice. Not a Democratic or Republican thing...but a gun, fired by the political regulars -- not the newer Obama turnout cohort but the regular off-year cohort -- at the heart of those who protect those in power, at bailouts, at spending.
Also: very easy alternate explanation: the economy sucks. States are really hurting. Governors are very unpopular. Their support is going to crater.