The Colorado Secretary of State's Office said proponents of the measure turned in nearly 169,000 signatures and, after reviewing a random sample, determined they submitted more than enough to get on the ballot set for later this year.

At its core, Initiative No. 109 restricts participation in K-12 and collegiate school sports based on a student's biological sex and requires schools and athletic associations to designate teams and sports as girls, boys or coed. It creates an exception, allowing a female student to participate on a male team if there is no female team available.

Additionally, the measure prohibits a government entity or athletic association from investigating a school over maintaining separate sports for females.

The fight over transgender athletes' participation is occurring against the backdrop of a major change in how the federal administration regards the issue following the election of President Donald Trump. One of the president's first executive orders was to declare that the policy of the federal government is to recognize only two sexes — male and female.

The White House also ordered all agencies to ensure "grant funds do not promote gender ideology."

The news of the initiative qualifying for the ballot also came on the heels of the U.S. Department of Education announcing that the Jeffco Public Schools district violated Title IX by permitting male students to access female bathrooms and compete in girls sports.

Initiative No. 109 includes a declaration that "males and females possess unique and immutable biological differences that manifest prior to birth and increase as they age and experience puberty." Physical differences, the measure adds, between males and females have "long made separate and sex-specific sports teams important so that female athletes can have equal opportunities to compete in sports while reducing the risk of physical injury."

Whether to allow transgender girls to participate in girls' sports is a focal point in America's culture war. Some 30 states have passed laws to ban transgender athletes from participating in girls' sports.

At the state Capitol in Colorado, Democrats have pushed for policies in the opposite direction, including legislation to penalize "deadnaming" and "misgendering" as discriminatory actions and to compel "publishers" to use a person's "chosen name" when asked.

This year, one bill initially included a requirement that family courts consider whether parents recognize their child's identity "as it relates to a protected class" when determining parenting time decision-making responsibility. Sponsors of that proposal have since removed that provision.