For over 80 years, Tucson has used partisan city elections. In 2009 the Arizona legislature passed a law, telling all cities that they must use non-partisan elections. On April 6, the Arizona Supreme Court ruled unanimously that if charter cities wish to hold partisan elections, they may do that, notwithstanding any law that the legislature may have passed. Here is the 24-page opinion. The case is City of Tucson v State of Arizona, cv11-0150.
Tucson is the only city in Arizona with partisan city elections. Generally, Democrats do better than Republicans in city elections in Tucson.