In the last few weeks, Republicans have blocked or vowed to kill: an extension of jobless benefits; the first real arms reduction treaty with the Russians in nearly a decade; the repeal of “don’t ask, don’t tell”; and, most significantly for the nation’s financial future, the expiration of unnecessary and expensive tax cuts for the rich.

Where has the president been through all this, as the sand runs out on a Congress with two Democratic majorities? He has issued a few mild statements and urged everyone to work together, when everyone knows the Republicans will refuse…

It may be that Mr. Obama still believes that bipartisan gestures can overcome extreme policy differences. But the rest of Washington woke up from that dream long ago. It has become a snare. Mr. Obama will have to spend the next two years contesting an implacable opposition. It would be a terrible mistake to begin by offering up core principles.