Until last night, Democratic moderates, the so-called blue dogs, could bask in the light of their candidate’s success in 2008. But now they must hear hoof beats behind them. The party discipline on which Obama depends to pass a health-care program that Americans reject by 42 percent for, 55 percent against (Rasmussen again) will only work if beleaguered Democratic incumbents can wrap themselves in Obama’s cloak and tough out the popular criticism. But the limits of Obama’s drawing power are readily apparent in the Republicans’ 20-point victory in Virginia and the race in New Jersey.

In the coming weeks, House Speaker Nancy Pelosi and Senate Majority Leader Harry Reid will be asking their troops to cast potentially career-ending votes for health-care changes, Medicare cuts, higher taxes, and fines on the uninsured. Whether they take that risk depends on their faith in Obama’s drawing power.

But the votes in Virginia, in particular, show the limits of Obama’s appeal.