COLUMBUS, Ohio — Governor DeWine vetoed a measure Friday that would have banned so-called “gender-affirming” medical treatment for minors and transgender athletes’ participation in girls and women’s sports, in a break from members of his party who championed the legislation.

GOP lawmakers hold enough seats to override DeWine’s veto, but if or when they would do so was not immediately clear. Both within and between chambers, Republican legislators have not been in lockstep this year.

In a news conference Friday, Mr. DeWine said he had listened to people on both sides of the legislation who “truly believe their position best protects children.”

He found that the bill would affect a small number of Ohio children, “but for those children who face gender dysphoria and for their families, the consequences of this bill could not be more profound.”

“Ultimately, I believe this is about protecting human life,” he said, announcing his decision to veto the legislation.

“Now, while there are rare times in the law in other circumstances where the state overrules the medical decisions made by the parents, I can think of no examples where this is done where it is not only against the decision of the parent, but also against the medical judgment of the treating physician and against the judgment of the treating team of medical experts,” he said. “Therefore, I cannot sign this bill as it is currently written.”

However, Mr. DeWine said he believed there were administrative actions that could address the main concerns of the bill and announced a three-pronged approach.

He is directing agencies to ban surgery on those under 18 as part of gender affirming care. He said he believes it’s a “fallacy out there that this goes right to surgery.”

He agreed with the Legislature that there was no comprehensive data on those who receive gender affirming care, and will direct relevant agencies to report findings to the Legislature and public about minors and adults seeking care.

Lastly, Mr. DeWine said his administration will draft rules and restrictions to prevent “pop up clinics or fly by night operations” so families receive “adequate counseling” regarding gender-affirming care.

Hundreds of opponents testified against Ohio’s multifaceted measure when it was moving through the Legislature, including medical and mental health providers, education professionals, faith leaders, parents of transgender children and transgender individuals themselves.

They decried the legislation as cruel, life threatening to transgender youth and based on fear rather than science.

The measure, which passed the Legislature earlier this month with only Republican support, would have prohibited Ohio minors from taking puberty blockers and undergoing other hormone therapies or receiving gender reassignment surgery that would further align them with their gender identity. It would, however, have allowed any minor who is an Ohio resident to continue treatment they are currently receiving.

Mr. DeWine’s veto departs from a nationwide trend toward passing such laws. Since 2021, more than 20 states have enacted laws restricting or banning such treatments, despite them having been available in America for more than a decade and long endorsed by major medical associations. Most of those states face lawsuits, but courts have issued mixed rulings.

The bill also would have required public K-12 schools and universities to designate separate teams for male and female sexes, and explicitly banned transgender girls and women from participating in sports that align with their gender identity. 

Supporters argued that banning transgender athletes from girls and women’s sports maintains the integrity of those sports and ensures fairness.

At least 20 states have passed some version of a ban on transgender athletes playing on K-12 and collegiate sports teams statewide. Those bans could be upended by a regulation proposed by President Biden’s administration that is set to be finalized early next year.