When John McCain clinched the necessary number of delegates on March 4, he became the presumptive Republican nominee.

When Barack Obama won North Carolina by double digits and gave Hillary Clinton a run for her money in Indiana on May 6, he became - by most accounts - the presumptive Democratic nominee.

So, that’s it - those are our presidential candidates for the general election, right?

Heck no, says Bob Barr, who on Monday announced his bid for the presidency as a Libertarian candidate. His announcement has created quite a buzz in the blogosphere as to how his candidacy will affect the race.

But before we analyze Barr’s impact, let’s learn a little bit about him. Barr is a former Republican congressman from Georgia, and not just any Republican congressman - it’s reported that he was one of the most conservative lawmakers in Congress when he served in the House of Representatives from 1995 to 2003. He’s been critical of Bill Clinton’s presidency - even leading the impeachment effort against him - but also critical of George W. Bush’s presidency, going so far as to leave the Republican party to become a Libertarian in 2006.

So where does he fit in in this race? He’ll be going up against 13 candidates for the Libertarian nomination, which will be decided at the party’s convention beginning May 22, but he’s already expected to win the nod.

Some say, as an ultra-conservative, he’ll nab votes from folks who would otherwise vote for McCain, but have been unsatisfied that he is not conservative enough (i.e. those people that keep voting for Mike Huckabee). In short, he could be the “Ralph Nader of the right,” says Newsweek.

Barr rejects this idea in an interesting interview with Newsweek. He says he’s not out to steal votes from anyone; he’s in it to win the presidency:

“…Does anybody getting into the race plan to ask the tough questions or plan to point out some of the areas where McCain is less conservative than he would like people to believe? Those pundits have no idea where my votes would come from, nor do they know about the issues I stand for. As a matter of fact, I suspect the votes I will get will come from folks who would be more inclined to sit out the election in the first place because there’s not a real conservative in the race. The votes are not going to come from people that are committed to voting for McCain.”

When confronted with the question of why he thinks he has a shot at the presidency when few third-party candidates have ever won a significant number of votes in the general election, Barr makes a good point:

“History provides no blueprint for the future in politics. We know that by looking at the dynamics of this particular race, which are very different in terms of the significant increase of new younger voters, the deep dissatisfaction with the status quo, the more than 70 percent of voters who believe that the country is on the wrong track, the cynicism about the current administration and the fact that I have not run for president before. I’m a very different candidate from the Libertarians and other candidates who have run in the past.”

Ok, so it’s not entirely true that history provides no blueprint for the future in politics. But he’s right in that this presidential race is one of revolutionary firsts: the first viable female candidate, the first viable black candidate - so why not the first viable Libertarian candidate?

In a race that has had as many unpredictable twists and turns as this one, I think we need to keep an eye on Bob Barr.