Republican Sens. John McCain and Jon Kyl are endorsing U.S. Rep. Jeff Flake in Arizona's U.S. Senate race.
Flake faces businessman Wil Cardon in the primary election battle for the Republican nomination for the Senate seat now held by Kyl, who is retiring.
The winner of the Aug. 28 Republican primary will face Democrat Richard Carmona in the general election.
McCain and Kyl announced their endorsements of Flake during a Friday news conference in Phoenix. The two incumbents called Flake a principled reformer.
Cardon's immediate reaction was to dismiss the endorsements as members of Washington's "old guard" sticking together.
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