The Trump administration is accelerating an investigation involving Minnesota in its fight to keep biologically male athletes out of girls’ sports. The probe surrounds the participation of a male athlete in a female-only high school softball championship game this month.

Federal authorities claim the male athlete’s participation was instrumental in the team winning the state title.

The U.S. Department of Health and Human Services Office for Civil Rights says it is now investigating the Minnesota Department of Education and the Minnesota State High School League for possible Title IX violations. The investigation will examine whether Minnesota engaged in discrimination on the basis of sex by allowing male athletes to compete on sports teams reserved for females. The U.S. Department of Education has its own investigation under way.

Title IX of the Education Amendments of 1972 prohibits sex discrimination in education programs and activities that receive HHS funding.  

“Females cannot be relegated to the sidelines under Title IX,” the director of the Office for Civil Rights, Paula M. Stannard, says in a news release. “As a recipient of Federal funds, Title IX requires Minnesota to ensure fair and safe opportunities for females to compete on sex-segregated teams – regardless of state law obligations.”

The investigation is part of a larger initiative to ban transgender athletes from competing in sports other than ones involving athletes with the sex assigned at birth.

President Trump signed the Keeping Men Out of Women’s Sports Executive Order shortly after returning to the White House. It states that allowing men to compete in women’s sports is “demeaning, unfair, and dangerous to women and girls, and denies women and girls the equal opportunity to participate and excel in competitive sports.”

On Wednesday, the U.S. Department of Education found that California and the state’s high school sports federation allowed biological males to participate in girls’ sports and use female locker rooms and bathrooms.

The state has 10 days to voluntarily agree to change its rules on transgender athletes or the case will be sent to the U.S. Department of Justice for possible legal action.

Maine has had its own running battle with the Trump administration over transgender athletes. Mr. Trump and Governor Mills got into a verbal spat over the issue during a public event at the White House in February. He warned her about complying with the executive order. Ms. Mills replied by telling the president that her state would “comply with state and federal law” and that she would “see you in court.”

“You better do it because you’re not going to get any federal funding at all if you don’t,” Mr. Trump said. The Trump administration has since sued the state over the transgender athlete policy.

A Republican lawmaker in the Maine house who has been a vocal opponent of transgender athletes competing in girls’ sports was censured in February after posting the first name and photo of a transgender athlete on social media. Representative Laurel Libby was blocked from speaking on the house floor and from voting on legislation.

Ms. Libby sued and the case made it all the way to the Supreme Court. Justices ruled that she cannot be barred from carrying out her duties as her lawsuit over the censure works its way through court. That allowed her to vote on bills but not otherwise speak on the house floor. On Wednesday, lawmakers voted to restore all of Ms. Libby’s rights to speak.

Other Title IX investigations are targeting high schools and colleges in Connecticut and North Carolina.