A few days ago Democrats thought they had Republicans splintered on the issue of extending the Bush tax cuts after House Minority Leader John Boehner said he might vote for a bill that only extended the lower tax rates for the middle class.

But Mr. Boehner suffered such a backlash from conservatives and the business community and was so beaten up by his own members that now almost no Republican dares speak out for that position. Right now it's the Democrats that are fractured. Last week Stan Greenberg, the dean of Democratic...