DALLAS (AP) — An upcoming sex exposition in Dallas that's billed as the largest of its kind in the U.S. and is expected to draw more than 15,000 people is being criticized by a mayor who says it goes against the city's position on the exploitation of women.

The three-day Exxxotica expo begins Friday at the Kay Bailey Hutchison Convention Center and will feature adult film performers, about 100 vendors, various seminars such as how to discover the ultimate orgasm, and other attractions like an "international twerk competition."

Dallas Mayor Mike Rawlings has sought ways to stop the event from being held on city property because he says it's exploitative.

Rawlings was not available for comment but The Dallas Morning News reports that he wrote to some people critical of the expo that he had asked city staff whether it was possible to halt it.

"I am particularly worried about the message that our playing host to this convention might send regarding our city's position on the sexual exploitation of women," the mayor wrote.

He was told by city attorneys that the city couldn't deny the use of the center just because of disapproval with the featured content, the newspaper reported.

Chicago, Los Angeles and Miami Beach have hosted Exxxotica in the past and its arrival in Dallas will mark the first time it'll open in the Bible Belt, in a metro area where 78 percent of residents identify with some segment of Christianity, according to the Pew Research Center, the highest metro rate in the country.

"The biggest fight we always have with this event is the misconceptions over it," Exxxotica director J. Handy said.

"We've done the show for 10 years and we're always looking for new markets for it," he said, explaining that he looks for large metro regions and the Dallas area, with approximately 7 million people, fits the bill.

But critics of the event say the city-owned convention center is no place to promote pornography, which they say is a "gateway" to sex-trafficking.

Katie Pedigo, executive director of Dallas-based New Friends New Life, which advocates for sexually exploited teen girls and women, says the public often doesn't understand that dating sites, sex conventions and other sex-related services perpetuate trafficking. Exploited women have spoken of porn being used to groom and prepare them for the sex trade, Pedigo said.

"The leap is not that great," she said.

Porn in the U.S. is estimated to be a $10 billion to $12 billion industry and Pedigo acknowledges that it's a lucrative business, but she notes, "The fact that it's popular doesn't make it right."

Another advocacy group, the Dallas Women's Foundation, wrote to Rawlings expressing "disgust" that the convention center will host Exxxotica. The group is asking the city to never again allow any similar event to be held at a public facility.

Handy says too often people judge Exxxotica conventions before they're even held. Efforts are made to keep the event tasteful, he said, and he notes that he's seen more salacious behavior at car shows.

He understands the criticism his event generates and says the right to condemn it is the same right he has to hold the show.

"I hope the groups that are up in arms about it are really able to see the quality of event that we hold," Handy said.