Although the best-known candidate coming into the convention, Barr was no shoo-in. He's a former Republican congressman with a record of casting some votes that most Libertarians reject, and most of the other top candidates had a far longer history in the Libertarian Party. That helps explain how it came down to the sixth round, where Barr defeated his top challenger Mary Ruwart with 54% of the vote.
Covered by C-SPAN, the nomination process showed an instant runoff-type voting process on live television. In each round, any candidate finishing last or dropping below 5% was eliminated if there were no majority winner. Then a new round of voting happened. This duplicates exactly the counting algorithm for instant runoff voting; the difference is that the voters had a chance to evaluate the preceding results and react to new information when voting again.
The progress of the rounds of the counting, reported on the Libertarian Party website was informative. For example, former U.S. Senator Mike Gravel was eliminated once the field was reduced to four, having picked up relatively few votes as other candidates were eliminated. After his elimination, Ruwart moved to the lead based on the votes of Gravel supporters, but Barr won when Wayne Root was eliminated. Root ultimately won the vice-presidential nomination in another contested, multi-round race.
Instant runoff voting of course also speaks to the manner in which Barr's candidacy will be treated. Like other likely third party and independent candidates this November like Ralph Nader (predicted by some to be on the ballot in 45 states), Barr has some very different views than likely major party nominees John McCain and Barack Obama. He is for reduced taxes like McCain, but for immediate withdrawal of U.S. troops from Iraq (along with other foreign nations) and repeal of the Patriot Act and Real ID law. His perspective is one that many American voters want to support rather than that of the major party nominees.
Yet already the reaction to Barr's candidacy is focused on where he might "spoil" John McCain -- the Democratic blog MYDD theorizes this might be in such states as his home state of Georgia and western states like Alaska, Nevada and Montana where Ron Paul was popular in the Republican nomination process earlier this year. On the Atlantic Journal-Constitution blog covering the LP nomination closely, those commenting already are showing bitterness at his potential "spoiler" impact.
And yes, there's another backer of instant runoff voting in this story: Bob Barr. He spoke highly of it when I was a guest on his radio show a couple years ago.