Why Can’t Democrats Understand This?

Paul Krugman, writing in New York Times Select, states (via):

But the Democratic presidential candidates — Mr. Obama in particular — have been facing a lot of pressure from the base to get specific about what they’re proposing. And the base is doing them a favor … There’s no conflict between catering to the Democratic base and staking out positions that can win in the 2008 election, because the things the base wants — an end to the Iraq war, a guarantee of health insurance for all — are also things that the country as a whole supports. The only risk the party now faces is excessive caution on the part of its politicians. Or, to coin a phrase, the only thing Democrats have to fear is fear itself.

This seems simple enough. A majority of Americans want us out of Iraq, sooner rather than later. A large majority of Americans, according to poll after poll, want universal health care. Why aren’t Democratic candidates jumping on this and enthusiastically supporting these issues?