WASHINGTON — Protesters targeted a Chick-fil-A food truck in downtown Washington on Thursday after the fast-food chain's president came out candidly against same-sex marriage on religious grounds.

"Ho-ho, hey-hey, Chick-fil-A is anti-gay," chanted a young crowd of around 20 demonstrators, with no apparent impact on the steady flow of patrons picking up chicken sandwiches and nuggets under the hot midday sun.

Mainly present in the southern United States, but expanding into other parts of the country, Chick-fil-A is as famous for its Christian values -- it never opens on Sundays -- as it is for its menu.

But its president Dan Cathy angered gay rights groups and their allies when he criticized marriage equality, saying last week that Americans are "inviting God's judgment" by accepting the idea that two people of the same sex can wed.

Elected officials in Boston and Chicago have gone so far as to tell Chick-fil-A to stay out of their towns, while the Jim Henson Company said it would no longer supply puppet toys to the family-owned chain.

Dan Rafter of the Human Rights Campaign, which organized the protest, told AFP that Chick-fil-A (pronounced "chick fillet") has a "long history" of funding groups that oppose greater rights for gays and lesbians.

"We're here to educate consumers," he said. "The Cathys have their personal beliefs, and that's fine... but there's a difference between personal beliefs and having them dictate your company's decisions and donations."

Some customers sympathized with the protesters, but only up to a point.

"The issue isn't the restaurant," said lawyer Joe Esposito, 26, as he waited to place his order. "It isn't that there's discrimination in the restaurant -- that would be illegal and not acceptable."

Law firm employee Catie Butler, 21, agreed.

"The food isn't anti-gay, just the owner," she said, describing Chick-fil-A's fare as "the best fast food there is."