DENVER — The Libertarian Party on Sunday picked former Republican Rep. Bob Barr to be its presidential candidate after six rounds of balloting.

Barr beat research scientist Mary Ruwart, who also sought the party's presidential nomination unsuccessfully in 1983, on the final ballot. The vote was 324-276.

Barr endorsed Wayne Allyn Root, who was eliminated in the fifth round, to be his vice-presidential nominee.

Barr left the GOP in 2006 over what he called bloated spending and civil liberties intrusions by the Bush administration.