Let's say you're a Democratic congressman from a swing district. Your constituency actually went for McCain in 2008 while sending you back to Washington on a split ticket. You had some rowdy town hall meetings during the 2009 August recess and decided to vote No on the House health care bill last November. Now the White House is saying that if you don't vote for the Senate bill in the coming weeks, the president won't appear in your district this fall or raise money for you on the road. And the DNC chairman is saying a Yes vote will be rewarded with support from Obama, Organizing for America, and the national party.
Here's the thing: What good would any of this do? To preserve your seat in an anti-incumbent, anti-Washington, anti-big government year, you have to distance yourself from Obama and the national Democrats anyway -- which is why you want to vote No in the first place!
Carrots and sticks don't matter. What matters is how your district will react to a Yes vote. And fear of reprisal -- not from Obama, not from Tim Kaine, but from the people -- is why Pelosi is still coming up short.