Obama vs. Huckabee: 47-43
Obama vs. Romney: 48-40
Obama vs. Palin: 52-40
Obama vs. Pawlenty: 50-30
PPP conducted a national survey of 766 registered voters from October 16th to 19th. The survey’s margin of error is +/-3.5%. Other factors, such as refusal to be interviewed and weighting, may introduce additional error that is more difficult to quantify.http://www.publicpolicypolling.com/pdf/PPP_Release_National_1022424.pdf
Ignore the part that does not respond or give a "don't know/other" response, and the proportions go to
Obama vs. Huckabee:
52.2 - 47.8 (looks much like 2008)
Obama vs. Romney:
54.5 - 45.5 (Bush 1988)
Obama vs. Palin:
56.5 - 43.5 (Eisenhower 1956)
Obama vs. Pawlenty:
62.5 - 37.5 (LBJ 1964)
Obama would probably defeat Mike Huckabee by winning the same states that Obama won in 2008 while adding Missouri and Arizona and making Montana and the Dakotas very shaky (but those three states yield only nine electoral votes). Huckabee would do nothing to cut into the Blue Firewall, but he might gain in the southern US in states that McCain won. That could be the best electoral result imaginable for the GOP, and it would still be a loss.
Romney would probably cut slightly into Obama's large wins in the Blue Firewall but at the risk of making the South shaky. He might swing Indiana and NE-02 but at the expense of making states like Tennessee, Georgia, and Kentucky shaky. He has no chance to win either Massachusetts or Michigan. In the best scenario for him he would force Obama to participate in a truly-national campaign instead of working on margins in a few "battleground" states in a polarized country as Obama did in 2008, which would be a good thing for America.
Palin is of course a political disaster. Economic realities could trump cultural resentments in 2012, and she can win only if she can unify those against Obama. If Obama succeeds in getting economic improvements in the areas that Palin declared the "Real America", then she loses in a landslide reminiscent of 1984.
I find it hard to believe that Pawlenty would get a McGovern-like result; the low polling for him may better reflect that he isn't well known. Where he is best known (Minnesota) he loses.