The South Dakota legislature is considering the nation’s first law that could send doctors to jail for treating transgender youths younger than 16 with hormone therapy or surgery, and the fight over the legislation is intensifying.

It has become so heated that after the legislation passed out of its first committee, the bill’s sponsor recently compared the doctors who treat transgender children to Nazis.

He did it this week, as the world is remembering the liberation 75 years ago of Auschwitz, the Nazi Germany-operated concentration camp in occupied Poland, where more than 1 million people, most of whom were Jewish, were killed in gas chambers.

“To me, that’s a crime against humanity when these procedures are done by these so-called doctors,” the bill’s sponsor, state Rep. Fred Deutsch (R), told Family Research Council president Tony Perkins in an interview on Wednesday. “You know, I’m the son of a Holocaust survivor. I’ve had family members killed in Auschwitz. And I’ve seen the pictures of the bizarre medical experiments. I don’t want that to happen to our kids. And that’s what’s going on right now.”

The State House’s Democratic leader denounced Deutsch’s comments as “ridiculous,” the Argus Leader reported.

“What doctors are providing is the best care they know for their patients,” state Rep. Jamie Smith (D) told the Leader.

During the Holocaust, Nazi doctors and scientists forced Jewish prisoners in concentration camps to undergo horrific medical experiments that often killed the victims or left them permanently disabled. They forcibly sterilized hundreds of thousands of people while practicing eugenics in an attempt to eliminate certain groups of people from the population.

Deutsch told The Washington Post late Monday that he did not intend to equate those crimes with the medical practices that would be affected by South Dakota House Bill 1057.

“I regret making the comparison,” Deutsch said. “I regret saying anything at all. It was pretty stupid.”

The South Dakota bill is the furthest along among a wave of proposals in red states to restrict medical treatment for transgender children. Similar bills have been introduced in South Carolina, Colorado, Florida, Oklahoma and Missouri. Politicians in Kentucky, Georgia and Texas plan to follow suit, as The Washington Post reported earlier this month.

Deutsch is Catholic, but was raised Jewish by a father who survived Auschwitz, the Argus Leader reported in 2016. The conservative legislation he’s supported has drawn harsh criticism in the past: Deutsch is the South Dakota representative who sponsored the nation’s first “bathroom bill” in 2016, which aimed to ban transgender students from using their preferred restroom at public schools. The state’s Republican governor at the time unexpectedly vetoed that bill after it was passed by the Republican-dominated state legislature.

Deutsch said photos he looked at showing surgical scars after sex-reassignment surgeries provoked an emotional response in him.

“You look at photos of the Holocaust and they’re gross,” Deutsch told The Post. “And then you look at the scars of these children and they’re equally — I don’t know if they’re equally — they’re also gross. Sometimes you see a picture, you hear a sound, you smell something that reminds you of something else and that’s all it was.”

Deutsch, who works as a chiropractor, still supports the bill he sponsored to punish doctors who perform surgical or hormone treatment on children under the age of 16, “because they can potentially sterilize children and potentially mutilate children.”

Hormone treatment, which can be used to delay puberty, is reversible and medical evidence suggests allowing transgender children to delay puberty until they are 16 can lower their risk for developing mental health conditions, according to the American Academy of Pediatrics. Children under 18 very rarely undergo sex-reassignment surgery.

He began drafting the bill after meeting people online, through social media like Twitter, who said they had suffered after hormone treatment or surgery and later regretted it, Deutsch told The Post. He said he talked to transgender children, their parents, transgender adults and “de-transitioned young people who spent time as a transgender person.”

The South Dakota Republican said he has never met or spoken to any of the doctors who offer hormone treatments to transgender patients in South Dakota. Fewer than four physicians in the state do so, The Post reported last week. It is unclear if any South Dakota doctors perform sex-reassignment surgeries.

After amendments were added to the bill, Deutsch’s proposal would bar hormone or surgical interventions for children under 16. The state would be allowed to charge doctors who provide those treatments with a misdemeanor and punish them with up to a year in jail and a $2,000 fine.

Opponents include civil rights advocates, Democrats and some Republicans who believe medical decisions should be made by patients and their doctors.

Among the supporters are conservative lawmakers and a group of radical feminists who increasingly oppose transgender rights.

At Wednesday’s committee hearing, an endocrinologist from California also employed the Nazi comparison in his testimony, the Argus Leader reported.

“The entire German medical establishment was behind atrocious human eugenics experiments in Nazi Germany, including untold numbers of children,” Michael Laidlaw said in the hearing, according to the newspaper.

Opponents of the restrictions point to medical best practices that suggest limiting treatment options for transgender youth can lead to poor results, including mental health issues like depression and suicide.

“The decision of whether and when to initiate gender-affirmative treatment is personal and involves careful consideration of risks, benefits, and other factors unique to each patient and family,” the American Academy of Pediatrics noted in a 2018 guide on providing medical care to transgender children.

Others have said the government shouldn’t make medical decisions for families. Civil rights advocates argue the proposal will further alienate transgender youth, potentially preventing them from receiving adequate medical care.

“Transgender kids, like all kids, deserve a chance to experience joy, to learn in a safe environment, to get the health care that they need, and to survive into adulthood,” Libby Skarin, policy director for the ACLU of South Dakota, said in a Jan. 15 statement opposing the bill. “When the government proposes laws that would stigmatize them and undermine their care, they lose those opportunities.”

But Deutsch has not been discouraged from moving forward with his bill, though he said he would not compare the doctors who would be affected by the proposal to Nazis again.

“Hindsight is 20/20,” he said. “I wish I wouldn’t have opened my mouth because it takes the focus off the purpose of the bill, which is to try to help children.”

Katie Shepherd is a reporter on The Washington Post’s Morning Mix team. Before joining The Post, she was a staff writer at Willamette Week in Portland, Ore.