I know that the dems want to go back to the South in 2004. Edwards can do it, but experience IMO stops him in the end among swing voters, unless Bush really screws up. Hillary won't sell in the midwest AT ALL. Blue collar guys hate her guts. John Kerry can win, but is a long shot IMO. Massachusetts is an albatross for liberals, more so than Texas is on the GOP end.
I keep coming back to three things.
1. Governors become presidents, not senators.
2. The dems keep saying they aren't giving up on the South. The next dem nominee will be probably from the south or midwest.
3. Whoever runs must sell in the Midwest - especially the toss ups of Missouri, Michigan, and Ohio. Penn isn't really midwest, but that could be thrown in here as well since it is closer to the midwest than Mid Atlantic politically.