On the evening that Donald J. Trump is expected to accept the Republican nomination, a coalition of gay rights groups will run a commercial that criticizes laws recently passed in states like North Carolina that limit which public restrooms transgender people can use.



The minute-long ad, which will air on Fox News during Mr. Trump’s speech, shows Alaina Kupec, a transgender woman from North Carolina, acting out a scene that advocates say occurs too often in states where anti-discrimination protections are not in place.

Ms. Kupec is eating with a group of friends and excuses herself to get up to use the restroom. But as she does, an employee at the restaurant intercepts her and insists that she use the men’s restroom instead.

“I can’t go in there,” she mouths to the man, who appears unsympathetic until two other women arrive and escort her into the women’s restroom. “When businesses can legally force me to use the men’s room, it puts me at risk for harassment and violence,” Ms. Kupec says. “Safety and privacy in bathrooms are important to all of us.”