Neither the manager nor any person in the employ of the city under appointment by, or employment of, said manager, mayor and council, or any other person authorized on behalf of said city to employ persons, shall take any active part in securing, or contributing any money toward, the nomination or election of any candidate or candidates for the office of mayor or members of the council, nor during the hours of service or duty to said city shall any such appointee or employee promote the candidacy or campaign of any person seeking office, elective or appointive, of the city, all under the penalty of dismissal from the service of the city.