The mayor of Denver has vetoed a vote to repeal the city's long-standing pit bull ban.
Mayor Michael Hancock said on Friday in a letter to City Council that after hearing from thousands of residents on the issue and carefully considering the matter, he could not "in good conscience support this legislation."
The Denver City Council on Monday voted to amend a code that banned pit bulls entirely from the Colorado capital. The amendment passed 7-4.
The ban has been in place for some 30 years.
Hancock said he spoke to experts in veterinary care and animal control to get a better understanding of what the change could have meant for the city.
"At the end of the day, I must ask whether passage of this ordinance would make our homes and neighborhoods safer or pose an increased risk to public safety? I have concluded that it would pose an increased risk," his letter read.
The founder of the American Pit Bill Foundation, Sara Ondrako, previously told ABC News that the ordinance was a "step in the right direction," but had numerous restrictions that would "still lead to a very discriminatory persuasion of pit bull type dogs."
"The problem has never been the dogs, it is and has always been irresponsible dog ownership.," Ondrako said in a statement to ABC News.
"The issue has absolutely nothing to do with the breed of the animal as researched and confirmed by experts in the field such as the American Veterinary Society of Animal Behavior, the Center for Disease Control, the American Kennel Club, the Certification Council of Professional Dog Trainers, the International Association of Animal Behavior Consultants, and even the American Pit Bull Foundation," she added.
Hancock said the restrictions included in the ordinance -- such as residents must register with Denver Animal Protection, have no more than two pit bulls, and get the dog a "breed-restricted license" -- were a valiant attempt to craft legislation.
However, he said, "less than 20% of all pets in Denver are currently licensed, which raises significant questions about the effectiveness of this proposed new system."
The cities of Lone Tree, Louisville and Commerce City have bans on pit bulls, according to ABC Denver affiliate KMGH. The City of Aurora is discussing whether to change its law.