Tyler Cowan, who supports more fiscal stimulus, nevertheless thinks liberals are too strident about demanding stimulus:

Reading the Keynesian bloggers, one gets the feeling that it is only an inexplicable weakness, cowardice, stupidity, whatever, that stops policies to drive a more robust recovery.  The Keynesians have no good theory of why their advice isn't being followed, except perhaps that the Democrats are struck with some kind of "Republican stupidity" virus.

Inexplicable? Hardly. Two factors are at work. First, Keynesian fiscal policy is unpopular. Most Americans think deficits are the primary problem during a recession -- indeed, their tolerance for deficit spending diminishes during a slowdown and expands during a boom. Conservative Democrats are currently terrified to vote for any bill that increasing the national debt. Second, the 60-vote Senate makes even popular actions difficult. As a result, economists associated with the administration understand that further stimulus, though desirable, is politically off the table.