Can a conservative former congressman who helped impeach President Clinton, is a board member of the National Rifle Association and has done contract work with the ACLU dent Sen. John McCain's presidential bid? That's exactly what Mr. McCain would face if Bob Barr, the former Republican who joined the Libertarian Party two years ago, wins his adopted party's presidential nomination. "Barr obviously is dangerous. At least he negates any possible Nader benefit," said David Norcross, a New Jersey member of the Republican National Committee and its Rules Committee chairman, arguing Mr. Barr would hurt Republicans at least as much as...