Senator Rand Paul’s libertarianism (support for drastically smaller government and suspicion of foreign entanglements and the security state) sets him apart from the rest of the potential Republican candidates for president.

That difference is almost certainly a net negative for his chances of winning the presidential race. But it also means he has a better shot than any of the other candidates for getting picked for the No. 2 slot.

Let’s say the Kentucky legislator makes a strong run — winning some states and coming close in others — but doesn’t win the nomination, a scenario that seems more likely than not. He has something going for him in the veepstakes that other Republican also-rans would not: a constituency that might well defect in large numbers from the party in November.

Assuming Paul loses, the Libertarian Party will have an easier task than usual: It will be able to concentrate its organizing among the people who voted for Paul in the primaries. That could easily amount to enough voters to deny Republicans a victory in the general election. (In other words, the libertarian candidate in this situation would be Ralph Nader in reverse.)

The winning Republican nominee would need Paul to campaign actively for him to prevent this scenario. But why wouldn’t Paul just go home to Kentucky to campaign for his own re-election? His Senate seat will be up in 2016.

Paul would then be the unusual politician who could actually secure some voters as the vice presidential nominee. That wouldn’t be the case for any of the other Republican candidates so far mentioned. There are plenty of viable conservative politicians in the party whose effect on a ballot would be more or less interchangeable. But there’s nobody else who would have a natural claim on Paul’s supporters.

That doesn’t mean Paul would get picked, of course. Among other things, the presidential nominee would have to worry that Paul would complicate efforts to portray Republicans as more pro-Israel than Democrats.

Because Paul has a distinctive constituency, though, he still has a pretty good shot of being on the ticket — even if he doesn’t make it to the top spot.

[Cross-posted at Bloomberg View]

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Ramesh Ponnuru is a columnist for Bloomberg View and a senior editor at the National Review.