But the new spring in the steps of Democratic lawmakers has not reversed the likelihood that there will be fewer of them next year. Mr. Obama’s signature on the health care law did not reduce a national unemployment rate that hovers around double digits and is likely to stay there through the November elections.

What it did was avert the collapse of confidence in Democratic governance that the failure of the president’s initiative would have engendered. That in turn could have triggered losses far worse than Democrats will otherwise endure, by dispiriting liberal true-believers even as independents and angry Republicans turned against them.

“Our base needed this kick,” said J. B. Poersch, executive director of the Democratic Senatorial Campaign Committee. Democratic strategists are not counting on much more of a political dividend than that…

“The substance is bad, and the process, which they managed to make an issue, is worse,” said Representative Tom Cole of Oklahoma, former head of the House Republicans’ campaign committee. “They have badly overplayed their hand.”