Although here at President Picker we're still predicting a Romney victory in the Republican Primary and an Obama win in the general election, it is now clear that Romney has failed to "wrap up" the Republican Primary as many predicted he would by now. Rick Santorum has clearly been annointed the new darling of conservative Republicans and his big wins in several states give him a real shot at the nomination. Gingrich's campaign is probably on its last legs now, while Ron Paul's substantial showings continue to be largely ignored by many who generally argue that Paul is less likely than Santorum or Romney to "break out" with enough votes to win the nomination outright.
Things get very interesting if Santorum, Paul, and Gingrich do well enough to thwart an outright victory by Romney, leading to a brokered Republican convention. This would be a very interesting scenario as we'd likely see mainstreamers still favor Romney while the hard liners - and often the most enthusiastic campaigners - will likely favor Santorum.
President Picker's Prediction: Romney / Santorum Ticket in 2012 vs Obama Biden.