When Nicole Talbot was 13, she was cast as a girl in a musical, but was told she couldn’t change in the girls’ dressing room.

Nicole had recently transitioned to a girl.

The people running the theater knew Nicole before that and wanted her to use the boy’s dressing room. Eventually, after sitting down with her mother, the theater relented and let Nicole dress with the other girls.

This is just one example of why Nicole’s mother, Jeanne Talbot, and other mothers of transgender children, are on a mission to uphold the Massachusetts law that protects their children and all transgender people.

“I, and hundreds of thousands of other families and transgender people, will fight with everything we have to protect our children and the transgender people who walk this path and have walked it long before we have,” Jeanne told me this week.

The state’s transgender anti-discrimination law, signed by Gov. Charlie Baker in 2016, is in jeopardy as its opponents try to repeal it on the November ballot.

Bay State voters will be asked whether or not they want to rescind the law, which prohibits discrimination against transgender people in public places such as hospitals, restaurants and malls, and allows them to use the restrooms and locker rooms of the gender they identify with.

If the measure is repealed, Jeanne said, her daughter and all other transgender people could be denied or refused service, including medical care.

“For Nicole, and all transgender people, it means that you’ll have to be looking over your shoulder all the time,” Jeanne said.

“To carry that fear and burden, every day, every minute, every where you go, isn’t right. It’s not equal.”

“My daughter,” Jeanne added, “could be refused medical treatment because she’s transgender, if this law is repealed.”

Nicole, now 16, was assigned male at birth. Jeanne coached Nicole’s T-ball games and took her to soccer games, but Nicole liked the color pink and dolls.

“It took me 12 years to figure out what she always knew, which is: She’s a girl,” Jeanne said.

Leading the charge to quash the transgender protection law is the “Keep MA Safe” campaign.

“When the state Legislature had an opportunity to exclude people with criminal histories or registered sex offenders they chose not to do that,” said Yvette Ollada, spokeswoman for the campaign.

“I don’t think anyone wants criminals preying on people in locker rooms, dressing rooms and bathrooms.”

But that argument falls flat with Jeanne and the Freedom for All Massachusetts coalition, which is seeking to uphold the transgender protection law. One of the coalition’s goals is to get 10,000 parents of transgender kids and cisgender kids to support it.

“It’s already illegal to commit a crime in any kind of place, including a public restroom, and nothing about this law diminishes that,” said coalition spokesman Matt Wilder.

Bridgewater mother Beryl Domingo’s son, Micah, was born a girl and transitioned during his senior year at Boston University. Beryl, too, fears a repeal. She called the attempt to get rid of the law a “kick in the gut.”

Micah, now 30, lives in Brooklyn. “If he were to come visit me,” she said, “he’d feel as if he’s really not fully protected in Massachusetts.”

Nicole told me she appreciates everything her mom, Jeanne, does for her and the work they do together to “make a difference in the world.”

Sadly, Nicole said, many transgender people don’t have supportive families.

“Just to see how time and time again she stands by me and stands up for who I am,” Nicole said, “that’s what every mother should do.”