Washington voters have approved a ballot measure barring transgender girls from participating in girls' school sports, reversing longstanding state guidance. The Associated Press called the race for Initiative 638 at 6:14 p.m. Wednesday, with 68 percent of the vote counted.

The measure led by about 56.6 percent to 43.4 percent, with roughly 1.25 million votes in favor and about 961,000 against, according to the AP's count.

Under Initiative 638, any student seeking to play on a girls' team must complete a biological sex verification process during routine sports physicals. Medical providers must sign a form confirming sex based on reproductive anatomy, genetic makeup or endogenous testosterone levels.

The measure, sponsored by the political action committee Let's Go Washington, overturns a state policy in place since 2007 that allowed transgender girls to compete on teams aligning with their gender identity. The Washington Interscholastic Activities Association, which regulates school sports in the state, says it knows of around 10 transgender students playing school sports.

Opponents, including the Washington State PTA, argued the verification requirement would put new barriers in front of girls who want to play sports, and critics said it would effectively require genital exams. Supporters described the measure as a fairness issue for girls' sports.

The result was part of a broader pattern on Tuesday: voters in Colorado, Nebraska and Arizona also weighed measures restricting transgender athletes or gender-affirming care for minors, and several passed or were on track to pass. Colorado's Proposition 134, which applies from kindergarten through college, appeared headed for approval, while Nebraska's Initiative 443 was projected to pass by about 68 percent to 32 percent.

The next statewide vote update in Washington is Thursday at 5 p.m. Counties certify results on November 24, and the state certifies by December 3.