I’m becoming increasingly convinced that Bob Barr’s candidacy could have a significant impact on the 2008 election. Here’s why.

1. The most recent poll suggests that Barr will draw only slightly more from Republicans than from Democrats. But I believe this is a distorted picture, because Barr will draw Republicans who would normally vote Republican, but Democrats who would not normally vote Democrat. (In any Presidential election, the Republican gets a decent number of Democratic votes, and the Democrat a decent number of Republican votes.) In particular, once potential Barr voters learn that he authored the Defense of Marriage Act, supports the Fair Tax, was one of the House managers of the Clinton impeachment, and proposed banning witchcraft in the military, his appeal will skew further towards right-wing libertarians as against left-wing liberaltarians (though he may keep some of these when they learn he has lobbied for marijuana decriminalization).

2. Some of Barr’s issues – civil liberties, opposition to the war – that will draw disaffected Republicans may cut into what would otherwise have been Obama’s vote totals as well as McCain’s (some of these voters would have otherwise defected to the Democrat over these same issues; others would otherwise have stuck with the GOP because of opposition to other elements in the Democrats’ platform). But one particular issue could pose real problems for McCain: gun rights. McCain does not have a good history with the gun rights crowd, while Barr is a true believer. Gun rights voters are a key part of the GOP coalition. If these voters are convinced that McCain will be lousy, and Obama won’t be much worse (which Obama might reassure them about by choosing a pro-gun-rights VP such as, oh, I dunno, Jim Webb), McCain could lose a small but important component of his base voters. That could make a difference in a close contest in Ohio, or Missouri, or Virginia, or Nevada.

3. To a lesser extent, Barr may be able to capitalize on immigration-restrictionist loathing for McCain. I actually doubt Barr is going to make a headline issue of immigration, because if he does that will devour his campaign and his priorities are elsewhere. But it’s not inconceivable that immigration-restrictionist activists wind up supporting him anyhow, as he’s more congenial than McCain or Obama are. If they get any traction, this once again cuts into a base McCain needs.

4. McCain has little positioning room to try to win back potential Barr voters, for two reasons. First, he is not trusted by the religious right. Among other things, that means he has to pick a VP who is acceptable to this wing. But the same kind of pick who would appeal to the religious conservative wing (Huckabee in particular) will be anathema to a certain sort of libertarian-leaning Republican. This will be an issue in debates as well; what if a question about “don’t ask, don’t tell” is put to the three candidates, and Bob Barr answers thusly. How does McCain answer the question? Second, McCain’s biggest opportunity vis-a-vis Obama is to try to solidify his support among blue-collar whites who Obama has had difficulty winning in recent primaries. But again, the appeals he’ll probably make to win over these voters – whether economic or cultural – may create an opportunity for a strong libertarian candidate to pick off other voters – “leave us alone” small government types who might have voted McCain anyway in a contest with Obama.

5. Here are the eight states where Perot earned better than 25% of the vote in 1992:

Maine (30%, Clinton won by 8% margin)
Alaska (28%, Bush won by 9% margin)
Utah (27%, Bush won by 19% margin)
Idaho (27%, Bush won by 14% margin)
Kansas (27%, Bush won by 5% margin)
Nevada (26%, Clinton won by 4% margin)
Montana (26%, Clinton won by 2% margin)
Wyoming (26%, Bush won by 6% margin)

Obviously, the Barr vote is different from the Perot vote (and much smaller), but I’m using this breakdown in part as an index of willingness to vote for a third-party candidate. Note that all but two of these states – Maine and Nevada – are generally solid GOP states, and only one is a generally solid Democratic state. Obama believes he has a stronger appeal in certain traditionally Republican states than recent Democratic nominees – particularly the High Plains states from North Dakota down through Kansas, and some of the Mountain states one click to the west (particularly Colorado and Montana). Polling has sometimes supported this contention as well. If Obama is running stronger than the average Democrat in states like Montana, a strong Barr campaign could put Obama over the top.

6. Bob Barr is from Georgia. In general, Obama is going to have a tough time in the deep South – even if he gets record African-American turnout in states like Mississippi, Alabama and South Carolina, overwhelming white support for the GOP will make an Obama victory impossible. But if Barr gets a significant vote in his home state, and Obama can generate historic levels of African-American support, there may be a window for Obama to contest Georgia, which would otherwise be out of reach.

7. McCain would like to position himself between the crazy right winger (Barr) and the party-line liberal (Obama). But given the issues Barr is likely to emphasize, McCain will have a hard time doing that, particularly if they wind up in a three-way debate. Barr will run on opposition to the war, protecting gun rights and civil liberties, and getting the government off our backs. The first positions McCain off on the right edge, and allows Obama to position himself as the sensible internationalist between the warmonger and the isolationist. The second, as noted above, McCain has to be very careful about given his history. The third will put Obama and Barr in the same camp, making it difficult for McCain to attack Obama (as Bush Sr. attacked Dukakis) as a card-carrying member of the ACLU. Only the fourth item gives McCain the opportunity to position himself as the sensible centrist watching the cash register, as against the crazed ideological opponent of government as such and the “tax-and-spend liberal” from Illinois.

8. Significant third-party candidacies do more harm to the candidate identified with the status quo. It was true in 2000, it was true in 1992 (and, I suspect, 1996, though then it didn’t matter), it was true in 1980, it was true in 1968, and the editors of the Chicago Tribune thought it was going to be true in 1948. I had figured that this year we’d see a significant anti-war, anti-immigration candidate running on a third party platform, but Barr will do in a pinch.