Republicans really don't like backing losers a second time. The one notable exception is Nixon ... and look at how well that turned out!
I think it is most likely Obama will win re-election. The economy is not great, but it is slowly improving. Barring a sharp downturn, Fed tightening, Libya going really badly, serious challenge from a True Progressive third party candidate, or major scandal, I really don't think anyone is going to unite the Republicans and Independents enough to defeat him.
So, let's combine these two ideas. Pick the Republican you would least like to be President and vote for them this time around. S/he will lose and not come back later. The runner up will be in a strong position, with much better name recognition in 2016, as Huckabee and Romney did last time. Just a silly idea I proposed over lunch the other day.