Just a quick thought on that Bob Casey endorsement. With Casey behind Obama, and Ed Rendell in Hillary's corner, we now have a weird mirror-image of the 2002 Democratic gubernatorial primary in Pennsylvania, in which Rendell bested Casey. Back then Rendell, who'd been a popular mayor of Philadelphia, carried that city by a huge margin and generally won over the state's affluent "wine-track" voters. Casey, by contrast, dominated among working class whites--which means most of the counties outside the Philly metro area. Here's how the Pittsburgh Post-Gazette described it at the time:

Rendell's victory told a Philadelphia story. The campaign managed to shift the center of gravity in Democratic politics to the east, reversing a recent pattern in which Western Pennsylvania Democrats voted in higher numbers than their counterparts in the Philadelphia region.

Casey led in all but 10 of the state's 67 counties, but those combined margins weren't enough to close the huge gap Rendell built among the voters who knew him best. It was a defeat not just for Casey but for the state Democratic organization that endorsed him and labor unions who backed Casey early and poured millions into his campaign.

Rendell was able to capitalize on a relatively heavy turnout in the Delaware Valley -- 35 to 40 percent in Philadelphia itself, according to preliminary estimates -- while Democrats elsewhere in the state were more inclined to stay home.

Mark Wolosik, who heads Allegheny County's elections division, estimated the Democratic turnout would be approximately 28 percent. In the Democratic primary for governor four years ago, by contrast, Allegheny County's turnout percentage was double Philadelphia's.

Rendell amassed a 150,000-vote margin in his hometown -- a margin roughly equal to his overall edge over Casey. Casey led in 57 of the state's 67 counties, but not by enough to overcome Rendell's Delaware valley totals. The Philadelphian won the surrounding suburbs by one double-digit margin after another -- Montgomery by 42,000; Bucks by 34,000; Delaware by 32,000, and Chester by 17,000.

One reason I was down on Obama's chances of getting anywhere close to Hillary in the upcoming primary is that he was basically looking at the Rendell coalition, except with less support among both working class whites in western PA and less support in Philly, where mayor Michael Nutter is backing Hillary and Rendell presumably still has influence. (Conversely, Hillary had the Casey coalition from 2002, but with a much better showing in Philly.) But with Casey now endorsing Obama, I suspect he'll be able to make up for some of the bleeding in Philly with a better-than-expected showing out west. I still don't think he can win, but he's got a shot of getting within ten points, which would be a moral victory of sorts.

Update: I see that Eve is skeptical of Casey's value to Obama. I agree that he doesn't have some huge machine that's now going to spring into action. But having a guy whose base consists of working-class white people vouch for you is important if, like Obama, you're having trouble convincing these same people to give you a look. It's as much about atmospherics as anything else. Or, put it this way: Before the Casey endorsement, a lot of these people may have known four things about Obama--that he was black, that he had a crazy black pastor, that there were rumors about him being a Muslim, and that yuppies think he gives a good speech. Now they know a fifth: That Bob Casey thinks he's a good guy. That obviously doesn't close the deal, but it's a pretty helpful addition. And Obama's pretty good at connecting with people once they're willing to hear him out. (Even working class people, though the evidence on that is obviously mixed.)

--Noam Scheiber