Richard A. Oppel of the New York Times offers a commendable article on the appeal of Ron Paul's foreign policy:

One recent national poll by ABC News and The Washington Post found that 45 percent of Republicans and independents who lean Republican said Mr. Paul’s opposition to American military interventions overseas was a major reason to oppose his candidacy, compared with the 29 percent who saw it as a major reason to support him. ...

... He also said military service members favored Mr. Paul in donations to Republican candidates. While there is no way to prove this because only itemized donations over $200 require occupations to be listed — information that is self-reported — a review by The New York Times of federal contributions suggests that active-duty and retired service members overwhelmingly lean to Mr. Paul. He received at least $115,000 in itemized contributions through Sept. 30, almost double that of all other Republican candidates combined.

So, Paul's stance on the military interventions abroad represents almost 1/3rd of the right half of the electorate who have a strong opinion on the subject, including a significant fraction of politically engaged service members: a losing total, but still a significant segment of public opinion that is represented by few other voices.