Andrew Sullivan and Ross Douthat wonder why Ron Paul doesn’t run again as the Libertarian Party nominee in 2008. Against Rudy Giuliani and Hillary Clinton, Paul could be, as Douthat puts it, “as formidable as any fringe-ish third party candidate could hope to be.”

I think there are good reasons why he seems disinclined to go the third-party route again. Paul’s social conservatism divided the Libertarian Party in 1988 and he only narrowly beat out American Indian activist Russell Means for the nomination. Paul’s showing was decent by Libertarian standards — about 432,000 votes; he was also the last LP nominee to finish in third place behind the major-party candidates — but it didn’t exactly set the world on fire. Paul has gotten much more attention as a candidate for the Republican presidential nomination.

Being a Republican has made it possible for Paul to win ten terms in Congress, a feat no Libertarian could replicate. He is planning on running for reelection, something that an LP bid would complicate. Finally, any improvement in Paul’s vote totals as a third-party candidate would owe in large part to his early Republican bid. But the longer he stays in the GOP race, the more sore-loser laws could hobble a third-party run. Paul is better off as a Republican.

UPATE: Though according to Rasmussen, he might not fare that well if he won the Republican nomination.