A major conservative has entered the race to be a third party challenge to John McCain, and that man is Bob Barr. According to FitsNews:
http://www.fitsnews.com/2008/03/31/barr-to-announce-pr
esidential-bid-next-week/Barr was a devout Republican congressman from Georgia, famous for leading the fight against Bill Clinton in the Lewinsky scandal.
So, what does this mean? Well, first Barr has to officially announce that he's running as a Libertarian (which he is expected to do next week) and then, secondly, he has to win the party's nomination. (Yes, third parties have conventions like anyone else, it's just that no one ever pays attention.)
If those two things occur, which, according to this report seems likely, Barr could certainly do some damage. Though he'd likely not win a single state, or even get close, even if he pulls 2-3%, that could be enough to swing the election if it's close. (Remember Nader '00?)
Still, Barr could potentially do even more than that. Barr could be that candidate for the far right, the Bush right. Will the Ann Coulter's and the Rush Limbaugh's of the world back Barr? Possibly. And what if he is to get the Ron Paul type of money, as Paul is rumored to be endorsing Barr.
An angry base and money is something Nader never had. So, now, let's imagine that, especially if he can get in the debates, Barr could potentially get 4-8% of the vote, especially pulling votes in the South. Would this push Virginia to Obama? Would this put more moderate Southern states like North Carolina and Georgia more within Obama's reach?
Whatever the answer is, it's not good for John McCain.