In response to the  Daniels , I’d point out three things. First, Republicans overwhelmingly vote Republican. George W. Bush won 93 percent of the Republican vote in 2004. Every winning GOP presidential candidate since national exit polls began has won at least 90 percent of the Republican vote (after years of dealing with conservative defectors, the Democrats are starting to catch up to this level of party unity — John Kerry won 89 percent of the Democratic vote in 2004). The number of Republicans who are going to vote Democratic, with or without Bob Barr, is likely to be very small.
Second, Republican defectors have tended to be moderate to liberal. Exit poll data on this point for the last two elections is hard to find, but in 1992 Bill Clinton won 15 percent of moderate Republicans (Ross Perot took another 21 percent), 17 percent of liberal Republicans, and only 5 percent of conservative Republicans. In 1996, Bob Dole beat Clinton 80 percent to 6 percent among conservative Republicans but only 48 percent to 44 percent among liberal Republicans. Clinton took 20 percent of GOP moderates that year. A fall 2004 Gallup poll suggests these numbers haven’t changed much. Moderate Republicans were three times more likely to be swing voters than conservatives and 13 percent of them said they were voting for Kerry compared to just 4 percent of GOP conservatives.
Third, I’ve yet to see any evidence of a large bloc of single-issue antiwar conservative voters. It doesn’t show up in the numbers among Republicans or the numbers among self-described conservatives. For example, Clinton won 20 percent of conservatives in 1996, Al Gore won 17 percent in 2000, and Kerry won 15 percent in the Iraq war election of 2004. In this year’s New Hampshire primary , the antiwar conservative Ron Paul did better among liberals (finishing a distant second behind John McCain) than self-described conservatives.
Maybe the moderate to liberal Republicans who voted for Paul would have voted for Barack Obama but will now prefer to vote for an antiwar ex-Republican instead. But past history suggests that most of them will hold their nose and vote for McCain while those who bolt will do so because they are moderate to liberal, not just antiwar. This is all a very longwinded way of saying I don’t see very many Obamacans and, among voters at large as opposed to conservative writers, even fewer Obamacons. Things will have to have changed a lot for Barr to tip the election to McCain by siphoning Republican votes from Obama.