Because of reports like this:

The nation’s current recession is likely to be the longest since World War II, and by some measures could be the worst since the Great Depression, a new Congressional Budget Office forecast said Tuesday. Without a major economic stimulus plan, “the shortfall in the nation’s output relative to its potential would be the largest in terms of both length and depth since the Depression of the 1930s,” said new CBO Director Douglas Elmendorf in testimony prepared for the House Budget Committee.

The politics are as brutal for the GOP as the economics:

Obama has done everything reasonable, and more, to move toward non-P-partisanship.  The overwhelming impression he's leaving for voters is one of reasonableness and accommodation. The public is clamoring for Washington to do something, anything. How'd you like to be a Republican member from Michigan or Indiana or Ohio?

That's why my advice is for the GOP to propose real entitlement reform. That's the real fiscal prize - even as they oppose the stimulus.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.