Should Santorum supporters in Pennsylvania vote for Romney? (Originally posted on Yahoo!'s "The Signal" Blog)

The future of the Republican primary hinges on Pennsylvania, where Rick Santorum must win his home state to hang on to his tenuous position in the race.

The political gambling markets that we watch so closely are extremely confident that Mitt Romney will ultimately win the nomination. This gives Santorum supporters in Pennsylvania an interesting choice when they go to the polls:

Option 1: Vote for Rick Santorum. By definition, supporters believe his positions align the closest with their own. Voting for Santorum sends a message to the Republican Party that the voter wishes the party would nominate a person with similar political philosophies.

Option 2: Hold your nose and vote for Mitt Romney. Presumably, the majority of Santorum supporters would prefer Romney to Obama in the White House in 2013. A vote for Romney helps him end the primary sooner and focus on Obama. Quite simply, it increases the likelihood that Romney wins the presidency in November.

Here is how an economist like me would approach the problem: First, think about how different your political opinions are from those of Santorum, Romney and Obama. If you feel that the distance between Romney and Santorum is very far apart, and that Obama is not much further from your positions than Romney, then it would be rational to vote for Santorum and send a message of support for his positions. If you feel that the differential between Romney and Santorum is relatively small, and that Obama is much further from your positions than Romney, then it would be rational to vote for Romney and give him a boost in November.

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