WASHINGTON (AP) — The U.S. Chamber of Commerce is stepping in to help a Republican preferred by the establishment in a bruising three-way Arizona primary in one of the most competitive House districts in the country.

The powerful business group is putting hundreds of thousands of dollars behind a television ad for state House Speaker Andy Tobin, filling a void for the financially strapped GOP candidate, who has been unable to spend on television advertising. Tobin’s two GOP rivals — businessman and rancher Gary Kiehne and state lawmaker Adam Kwasman — are already on the air with ads.