JACKSON, Miss. — Mississippi Republican Gov. Tate Reeves signed a bill Thursday to ban transgender athletes from competing on girls or women's sports teams.

Mississippi is the first state this year to enact such a ban, after a federal court blocked an Idaho law last year. Mississippi's Senate Bill 2536 is set to become law July 1, although a legal challenge is possible.

More than 20 states are proposing restrictions on athletics or gender-confirming health care for transgender minors this year. Conservative lawmakers are responding to an executive order by Democratic President Joe Biden that bans discrimination based on gender identity in school sports and elsewhere. Biden signed it Jan. 20, the day he took office.

Wyatt Ronan, a spokesman for the LGBTQ civil rights group Human Rights Campaign, said the Mississippi bill would be the first transgender sports ban signed into law this year. Idaho enacted a similar law in 2020 that has been blocked by a federal court.

Reeves has three daughters who play sports and he said March 4 on Twitter that Mississippi's bill would "protect young girls from being forced to compete with biological males for athletic opportunities."

"It's crazy we have to address it, but the Biden E.O. forced the issue," Reeves tweeted that day. "Adults? That's on them. But the push for kids to adopt transgenderism is just wrong."

Chase Strangio, a transgender-rights attorney with the national ACLU, said the Mississippi bill "is very vague and seemingly unenforceable."

"Unfortunately, there is already rampant discrimination against trans youth in Mississippi, which means people are already driven out of sport," said Strangio. "Gov. Reeves's statement makes clear that this isn't about sports at all, this is about attacking trans youth and stopping kids from being trans — a dangerous project with deadly consequences."

The Mississippi Senate passed the bill Feb. 11, and the House passed it March 3. The votes were largely along party lines, with most Republicans supporting the bill and most Democrats either opposing it or refraining from voting.

Republican legislators who pushed the bill gave no evidence of any transgender athletes competing in Mississippi schools or universities.

Supporters of bills such as the one in Mississippi argue that transgender girls, because they were born male, are naturally stronger, faster and bigger than those born female. Opponents say such proposals violate not only Title IX of federal education law prohibiting sex discrimination, but also rulings by the U.S. Supreme Court and 11th U.S. Circuit Court of Appeals.