Prediction markets leaning toward safe choice for Romney’s running mate

With anywhere from days to weeks remaining in the long and tortured period of speculation over Mitt Romney's running mate, the Signal is increasingly convinced that either Ohio Sen. Rob Portman or former Minnesota Gov. Tim Pawlenty will get the nod. The prediction markets currently give them a 35 percent and 16 percent chance of victory, respectively. In other words, there's better than a 1-2 chance that Romney will opt for the safest choices available.

You could be forgiven for needing a refresher on which of these two politicians is which. Portman and Pawlenty are both white males in their 50s with records as reliable conservatives, not firebrands. Either would provide Romney cover from the right while providing a sense of prudent sensibility to the rest of the country. These men both provide a moderate benefit, credibility with the right, with little potential cost.

Sources: Betfair and Intrade

From a strategic standpoint, the biggest difference between them is that Portman is from a swing state. But our model of the past 10 election cycles suggests that the running mate's home state has very little influence in electoral outcomes. Campaigns seem to agree. In the past few cycles, the candidates haven't generally been drawn from competitive states.

While popular speculation continues to swirl around the dynamic first-term senator from Florida, Marco Rubio, and the outspoken first-term governor from New Jersey, Chris Christie, their likelihoods have plummeted in our predictions over the last several months.

Like the Supreme Court, however, this is a decision that rests with a small group of people, not a large mass of voters whose behavior we can analyze and model. The Republican pick in 2008 was certainly someone we would have given negligible likelihood of being the choice. Yet for vice-presidential choices we have a long track record of similar decisions and a clearly defined objective—winning the presidency—for the single decision maker. So despite the small number of voters in this election (one), our information level is reasonable high.

Follow along in real time with and see our full list of likely vice-presidential candidates.

David Rothschild is an economist. He has a Ph.D. in applied economics from the Wharton School of Business at the University of Pennsylvania. Follow him on Twitter @DavMicRot and email him at