DENVER (AP) – Colorado lawmakers on Thursday abandoned legislation to make it harder for parents to opt their children out of vaccinations, as time was running out in the legislative session. The bill drew big crowds of vaccination opponents to the state Capitol and came amid the nation’s worst outbreak of measles in 25 years.

Backers of the proposal, including the American Academy of Pediatrics, said it was needed because the state’s vaccination rate is around 89%, lower than the national average of 94% and not high enough to create “herd immunity” and avoid large outbreaks.

Colorado allows parents to opt their children out of vaccinations required by most schools and day care centers for medical reasons with a doctor’s note. Those who object to inoculations for religious or any other personal reason can also submit a statement to be exempted.

The bill would have created standardized forms for medical and other exemptions and would limit the reasons for a medical exemption to those allowed by the federal Centers for Disease Control and Prevention.

It would also require those seeking a religious or personal exemption to initially apply in person at their local health department or the state health department. Future exemptions could be requested online.

Gov. Jared Polis expressed concerns about the in-person applications, so his approval of the bill was not assured.

“Republicans were not willing to let the vaccine bill come to a vote without hours and hours of debate, which would have prevented us from delivering on priority bills,” including health care and education, said Senate Majority Leader Stephen Fenberg, a Democrat.

In the state House, a handful of lawmakers consoled a stunned Democratic Rep. Kyle Mullica, a prime sponsor of the bill.

“I cannot explain what just happened,” said Mullica, a trauma nurse from suburban Adams County. “We worked so, so hard on this. We can’t just stand by when there is a public health crisis going on in this country.”

RELATED: Rep. Kyle Mullica, Lawmaker Behind Vaccine Bill, Receives Death Threat: ‘Leave My Family Out Of It’

Stephanie Wasserman, executive director of the nonprofit Colorado Children’s Immunization Coalition, said legislators put politics over the health and safety of children.

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