Michael Badnarik, a computer programmer from Austin, Texas, won the Libertarian Party's presidential nomination in Atlanta.
Badnarik, 49, defeated former Hollywood movie producer Aaron Russo on the convention's third ballot, with former radio host Gary Nolan's endorsement.
"If I can win the nomination, there's no reason I can't win this election," Badnarik told convention delegates.
Formed in 1971, the Libertarian Party stresses the rights of individuals over the power of government.
It says it has nearly 600 elected officials nationwide.