The Presidency is just a bonus for the GOP on the tails on a declining economy.
It'd far more reasonable for them to try and win the Senate and just have a non-threatening Presidential candidate like Huckabee or Romney who won't scare off the voters.
Do you think Obama's the new FDR or something? It seems like you think that it's impossible for Republicans to win the Presidency in 2012.
Presidents far less successful or interesting than FDR have won re-election without contest.
It's not impossible, but things are clearly not trending in that direction. He is far more popular than the Democratic party as a whole and the opposition doesn't have a home run hitter.
At best, I see at as 2004. Bush could have been beaten, but the Democrats couldn't have beaten Bush. The race might be close, but on election night the result will only be in doubt to Diebold conspiracy theorists.