The National Organization for Marriage (NOM) will launch its #FreeSpeechBus on Thursday in New York City, with appearances at Trump Tower and the United Nations.

The orange bus' message reads: “It's Biology: Boys are boys … and always will be. Girls are girls … and always will be. You can't change sex. Respect all.”

The bus is sponsored by NOM, the International Organization for the Family (IOF), whose formation was announced by NOM President Brian Brown in December, and a coalition of global groups opposed to LGBT rights.

The campaign first arrived in Spain, where a similar bus read: “Boys have penises. Girls have vulvas. Don't be fooled. If you are born a man, you are a man. If you are a woman, you will continue to be one.”

City leaders in Madrid banned the bus on the premise that it was discriminatory and could incite hate crimes.

A billboard with a similar messaged appeared last week in Guatemala. CitizenGo, a network of social conservatives which includes Brown on its board, took credit.

The U.S. version of the campaign is backed by NOM, IOF and CitizenGo. In a press release, the groups said it “is meant to affirm a biological basis for gender and to criticize 'gender ideology.'”

Brown, who helms NOM and IOF, added that gender is “fixed.”

“It's biology, not bigotry,” Brown said. “Men and women were created equally, each given a gender that is fixed, immutable and complementary. Rather than perpetuate a lie that gender can be changed based on emotions and feelings, we should encourage people to embrace and love who they were made to be.”

OutRight Action International condemned the bus, saying that it promotes a harmful and untrue message and encourages “violence against trans individuals.”

“Free speech is a constitutional right, but language has consequences,” said Jessica Stern of OutRight Action International. “Trans youth already have an extremely high risk for violence, discrimination, and suicide. Broadcasting a message that erases and denies the reality that transgender and intersex children and youth exist is irresponsible, factually misleading, disrespectful, and dangerous. This vehicle is part of the reason trans youth are driven to suicide.”

Scheduled stops include New Haven, Boston, Philadelphia and Washington, DC.