Computer engineer Jonathan Morey says, "I have never voted for a Republican, ever." Nathan Hansen, a lawyer, says, "I've been a Republican all my life." Yet a political meeting in St. Paul, Minn., brought the 31-year-old friends together for the first time -- in support of presidential candidate Ron Paul. Officially, Mr. Paul is a Republican, elected to Congress 10 times and now running for the party's presidential nomination. But the party label hardly describes the obstetrician from south of Houston. And it certainly doesn't explain his appeal to a growing, if still small, number of voters across the political...