Making good on its threat to target Texas Rep. Ron Paul (R), the New Jersey-based National Organization for Marriage has released an advertisement in Iowa that brands him a "radical" who is unwilling to defend traditional marriage.

“There’s five days left,” Brian Brown, president of NOM, told the New York Times. “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.”

Paul has become the GOP’s leading presidential candidate in the crucial Iowa caucuses and is the only candidate that has not signed NOM's marriage pledge. Candidates who signed the pledge vowed to support a federal marriage amendment defining marriage as between only one man and one woman, protect the Defense of Marriage Act in court, appoint conservative judges, and create a presidential commission to investigate harassment of same sex marriage opponents.

The 30-second ad claims that Paul has "called for abolishing marriage altogether."

"You may think of Ron Paul as a conservative, but when it comes to marriage he is a radical who would destroy traditional marriage in America," the ad concludes.

Paul has said he personally believes that marriage is between one man and one woman, but the libertarian-leaning candidate opposes a federal marriage amendment, because it would interfere with a state’s right to define marriage for itself.

Watch video, uploaded to YouTube, below: