On almost any issue, kids can make an argument more compelling.

“Kids are more of a blank canvas,” says Elizabeth Wilner, who studies political advertising for the firm Kantar Media CMAG. “The standard prejudices and thoughts people might bring to a particular issue tend to get left by the wayside when they’re watching an ad that features a kid.”

People can easily pass judgment on gays and lesbians or condemn those who came to the United States illegally. It’s much harder to dismiss their children.

“I think it immediately unfangs the opponent,” says Mark Fitzloff, an executive at the advertising firm Wieden + Kennedy. “Because what are you going to do? You’re going to attack children? I mean, it’s a smart chess move to anticipate your opponent’s next move and pull the power out of it.”