Citing not enough room, the Madison Public Library has cancelled a planned Saturday event by conservative organization Moms for Liberty.

“The Moms for Liberty organization had planned to feature Brave Books in a meeting room at Madison Public Library. Due to the event’s anticipated attendance increasing beyond the Library’s capacity, the Library will be unable to host the event,” the library said in a news release today.

The organization has replied that cancelling would be unlawful and unconstitutional. Organizers have given the library until noon Friday to open its doors to the group or face court action. Moms for Liberty’s Madison County chapter had planned to give away copies of actor-writer Kirk Cameron’s book “As You Grow,” and said the actor would be present Saturday.

People had also planned a counter protest outside the library, according to social media posts, but that was not cited in the cancellation.

Organizers originally projected 20 attendees, the library said, but library staff said they learned Tuesday that organizers were expecting more than 300 people. The library called that “a number that far exceeds any meeting room capacity within the Huntsville-Madison County Library System.”

The library said it “explored options” to make the event possible consulting Madison City Police, the Madison City Fire Marshall and city officials. The police and fire departments recommended an alternate location, the library said.

“The Moms for Liberty group failed to apply for an event permit in advance,” the library said in its news release, “and it was determined that city resources cannot support an event of this size on such short notice. Alternative accommodations have been recommended to the organization to ensure a safe and well attended event.”

The Moms for Liberty website says the group is “dedicated to fighting for the survival of America by unifying, educating and empowering parents to defend their parental rights at all levels of government.” It called the library’s response “phantom ‘security concerns’” that the content of its speakers’ remarks would generate those concerns. “It strains credulity to cancel and event that may be over capacity when the library staff could simply operate on a ‘first-come, first-serve’ basis,” the group’s attorney said.

If the library continues to refuse space for the event, “We are prepared to vindicate this violation of our client’s civil rights in court,” First Liberty attorney Jeremy Dys said. Dys copied his letter to Alabama Attorney General Steve Marshall.