The thing to remember here is that the Republican candidates are not yet campaigning against Obummer. They're campaigning against one another.
Obummer, meanwhile, IS campaigning against the frontrunners... pushing them down while not meeting any directed resistance.
That will change in the coming months. The 2012 election won't be much of a contest. The economy is heading downward again, and it will take the incumbent down with it.

Gold is $1,581/oz today. When it hits $2,000, it will be up 26.5%. Let's see how long that takes. - De 3/11/2013 - ANSWER: 7 Years, 5 Months