TriMet has been fielding complaints for putting a controversial OkCupid ad on its buses for weeks.

First came complaints from a local woman who found the ads offensive for their stereotypical, sexualized portrayal of lesbians, and now from a notoriously anti-LGBTQ organization that wants the ads removed for religious reasons.

The image under scrutiny features a lesbian couple next to the bold letters "DTF." And this week, CitizenGo, a Madrid, Spain-based organization, started a webpage asking for signatures to get the ads removed from TriMet buses.

"OkCupid's 'DTF' advertising campaign promotes lesbian sex, prostitution, drug use, and promiscuity," the online petition reads, "and it will be viewed by millions, including children, in public spaces."

This type of religiously-fueled, anti-queer campaigning is nothing new for CitizenGo.

The group first made U.S. headlines last March, when a "Freedom Speech Bus" it conceptualized began touring the East Coast. The bus—which was plastered with the statement, "It's biology: boys are boys, girls are girls. You can't change sex. Respect all."—received criticism for its overtly transphobic message. New Yorkers eventually took spray paint and hammers to the vehicle.

So far, the group's petition to remove the OkCupid ad has received 4,250 signatures. But OkCupid and TriMet say they aren't fazed by the effort.

"OkCupid stands behind being inclusive, welcoming and allowing people to be whoever the F they want," says OkCupid's CMO, Melissa Hobley. "There is no place, anywhere, for the kind of homophobic, transphobic, and generally close-minded message that CitizenGo is notorious for spreading."

For its part, TriMet says it is legally obliged to run the ads—regardless of if they offend people—because of an Oregon Supreme Court ruling that prohibits the agency from restricting free speech.

"About those OkCupid ads," the transit agency tweeted, "We cannot reject an ad if its message is protected by the Oregon Constitution—which is usually the case—because it counts as free speech and is fair game."

"So if you see an ad on the bus or train that you don't like," it added, "we hope you'll keep this in mind."