The proposed amendment was submitted by the American Federation of State, County and Municipal Employees. If passed, it would change the way all city employees are hired and make the process similar to the way firefighters and police hired.

In a memo sent to city council members Friday, Ott said the change would cost the city hundreds of thousands of dollars the first year and millions more each year thereafter.

In response, the union sent a memo saying the city manager's estimates were off base. They say the change would help level the playing field between public and civilian employees. The union also argues other major cities, including Dallas and Houston, have similar models.

Council members will consider the amendment at Thursday's meeting.