In an exclusive interview with Reason, Austin Petersen, the second-place finisher (to Gary Johnson and John McAfee) in the Libertarian Party's presidential primary, explains why he is running for the U.S. Senate in his home state of Missouri—as a Republican.While he may have switched parties, Petersen's platform is exactly the same one he put forth while making his run at the LP nomination: He is staunchly anti-war and is calling for an audit of the Pentagon; favors school choice, drug legalization, and gay marriage; wants to simplify and reduce taxes while cutting overall spending; pushes criminal justice reform, an end to regulations large and small. He remains opposed to abortion, which is a minority position among libertarians, but calls for strong religious liberty and a total repeal of Obamacare/Trumpcare.Missouri is an open primary state, meaning that voters don't need to be members of a party to vote in its primary (August 2 in Missouri), and Petersen hopes to turn out LP members and independents for the GOP contest.The incumbent, Democrat Claire McCaskill, is widely regarded as one of the most vulnerable sitting senators in the country and no high-profile Republicans have publicly entered the race.