The new Diageo-Hotline poll:
As you can see, Obama does far better than Clinton against each potential Republican nominee. He also leaves a few more undecided, because some of those undecideds switch over to the Republican when Clinton is on the ballot. Edwards' numbers a similar to Obama's, but with even more undecideds. The exception is against McCain, when he gets smoked 39%-47%.
SurveyUSA has a whole slew of post-Iowa (and some post-New Hampshire) state-based head-to-heads. Rather than make this a ridiculously long post with all of the data, I'll just summarize it.
Ohio: Obama and Clinton crush Romney and Giuliani by 8-12%. They both tie Huckabee and lose to McCain (although Clinton holds him to a 2% win).
Iowa: Obama crushes all opposition by margins of 17-30%. Clinton wins big against Romney and Giuliani, but ties Huckabee and loses to McCain by 4%.
Missouri: Obama loses by 10% to McCain and Huckabee, but beats Romney and Giuliani by smaller margins. Clinton loses to McCain and Huckabee by 6% and 2%, respectively. She beats Romney by 7% and Giuliani by 4%.
Oregon: No Republican other than McCain comes even close here. McCain? He beats Clinton by 4% and ties Obama.
Washington: Same deal as Oregon, except McCain loses to Obama by 9% and only beats Clinton by 3%.
Virginia: Clinton beats Romney by 8%, Huckabee by 7%, and Giuliani by 6%. Obama beats those same Republicans, but only by 4%, 5%, and 1%, respectively. Both lose to McCain by large margins.
That does it for the swing states. Now, can either Clinton or Obama expand the map in places like Alabama, Kansas, and Kentucky?
Alabama: No one comes close, although Clinton loses by an average of 13.5% to Obama's 26%. Anybody a little bit racist?
Kansas: Every match-up not involving John McCain is extraordinarily close. McCain crushes both Democrats by double digits. The only solid win is for Clinton over Giuliani by 6%.
Kentucky: McCain and Huckabee beat both Democrats in routs. Giuliani beats Clinton by 2% and Obama by 6%. Romney loses by 6% to Clinton, but by only 1% to Obama.
Clinton looks like the stronger nominee, with the notable exception of Iowa. That's not to say that anyone should compound the mistakes made by Iowa, New Hampshire and Michigan voters who cast their ballots for her. McCain is clearly the strongest nominee for the GOP, followed by Huckabee, who is nearly as strong, but can't open up opportunities in blue states like Oregon and Washington. Giuliani and Romney both look like they'd be pathetic nominees, but Romney might be a touch worse.