PHOENIX — Arizona cities are losing their right to demand that nonprofit groups seeking to sway local elections divulge who is financing the effort.

Gov. Doug Ducey late Thursday signed legislation that pre-empts local ordinances requiring these groups to register as political action committees. The measure, which takes effect this summer, also makes any effort to identify contributions off limits. It was promoted by Rep. Vince Leach, R-Tucson.

By a margin of 9-1, Tempe residents voted earlier this year to mandate disclosure of spending on local races. Tempe is a “charter city,” constitutionally entitled to enact laws on strictly local matters. And the Arizona Supreme Court has twice ruled that local elections in charter cities (which include Tucson) are not subject to state oversight.

It is not known whether Tempe will challenge the new law as an unconstitutional infringement on local powers. Other charter cities, including Phoenix, are considering similar measures.

There also is currently a statewide initiative drive to put a “right to know” provision in the Arizona Constitution to require that all sources of $10,000 or more be made public.

Ducey himself has been a beneficiary of anonymous campaign donations. He has said he believes in transparency, but also that there’s a valid reason to allow people to contribute anonymously to campaigns.

“People have a First Amendment right as well to participate and not be bullied,” he said.