Dallas Mayor Eric Johnson announced Friday that he is switching parties and will serve as a Republican-affiliated mayor of the blue-leaning city.

While the Dallas mayoral office is nonpartisan, Johnson previously served as a Democrat in the Texas legislature. He slammed his former party in an op-ed for Wall Street Journal published Friday, blaming Democratic policies for “exacerbated crime and homelessness.”

“The future of America’s great urban centers depends on the willingness of the nation’s mayors to champion law and order and practice fiscal conservatism,” Johnson wrote. “Our cities desperately need the genuine commitment to these principles (as opposed to the inconsistent, poll-driven commitment of many Democrats) that has long been a defining characteristic of the GOP.”

He added: “In other words, American cities need Republicans—and Republicans need American cities.”

Johnson’s announcement makes him the only Republican among the mayors of the 10 most populous cities in the US.