The antiwar, pro-gold, libertarian presidential candidate Ron Paul tells me he would rather be riding his bicycle than speaking to another reporter on a Thursday afternoon. "My vice is that I'm obsessed with exercise," says the Republican congressman from Texas. But running for president does not exactly disagree with him. All day long, he has been hustling from one press appearance to the next, a high-energy bundle packed into a lithe 71-year-old frame. His brown eyes sparkle with fire as he blurts out one big adjective after another. "Preposterous," he says of Rudy Giuliani, who accused Paul in mid-May of...