Presidential elections are often a response to the perceived weaknesses and strengths of the existing president.
To the right wing, Obama is a leftist and their design for their run at the presidency will be to run as free market right wingers against Obama the leftist/socialist.
But, to the moderate wing of the Republican Party, say Romney or Huntsman, Obama is an ivy league professor trapped in the wrong job who doesn't have the skill set needed to be a competent, decisive leader.
I think that if the Republicans have any chance at replacing Obama, they must run on the issues of competent leadership, especially in the arenas of the economy and foreign policy. If they can dodge the true believers demanding ideological purity, they may even have a chance to win.