It sounds like the right idea, but I remember hearing about a study recently that said trying to send out a "this rumor isn't true message" only serves to reinforce the original rumor. The summary was that people hear the original, and when the hear the rebuttal, they only remember the original rumor anyway. Additionally, having a rebuttal come from a "respected" news source (the candidate themselves or mainstream news) gives further power to the rumor.

I wish I had a link handy because it was an interesting study.

It's clearly an 16th century relic of the Catholic Church, which was used to mark all members of the church so they would be assured entry into the pearly gates. It was frequently called "God's Hall Pass" by critics.