Ron Paul's opposition to a constitutional amendment banning gay marriage is the subject of a new ad sponsored by the National Organization for Marriage (NOM), the nation's most vociferous opponent of gay marriage.

Paul's sharp rise in the polls has lead to speculation that the Texas Congressman could be the big winner of next week's Iowa caucuses.

The 30-second ad opens with the suggestion that Paul is not a legitimate contender, “All the major presidential candidates have pledged to preserve traditional marriage,” and quotes Paul as saying that marriage is a private affair.

“Ron Paul has even called for abolishing marriage altogether,” a male announcer says. “You may think of Ron Paul as a conservative, but when it comes to marriage, he's a radical who would destroy traditional marriage in America.” (The video is embedded in the right panel of this page. Visit our video library for more videos.)

NOM President Brian Brown told The New York Times it was important for caucusgoers to know where Paul stood on the issue: “There's five days left. This is the critical period. This is a very unique election. People are still making up their minds in Iowa, and that's why it's important we do this now.”

In recent days, Paul has also battled charges that he's “uncomfortable” with gay people.