Most Americans don't give a flying fuck about Gadhafi.
Obama will stand on the debate stage and say, "Gadaffi killed 200-something americans. Raise your hand, Mr Pawlenty, if you would prefer that MFcker was still in power..."
The repub will then have to hem and haw about some minor point of how obama handled it (appearing petty in the process) then will return to say "yes, I am glad we killed the guy who killed americans".
Obama kills a terrorist leader, it's a win. Sorry. It is. If Kadaffi is sitll in charge in 2012, it's a major obama LOSS as well.