The Flake ad doesn't mention Cardon by name, nor does it refer to the Democratic nominee, Richard Carmona. But it does take a veiled swipe at Cardon, who a recent poll shows is 22 points behind Flake in the primary.
"Named a taxpayer superhero," the narrator says of Flake. "Fella running against Jeff tries to say otherwise, but we all know better."
Coming to Cardon's aid on Tuesday was Arizona Rep. Trent Franks (R), who backed Cardon over Flake in the GOP primary.
"Wil Cardon understands what Arizona needs in Washington," Franks said in a statement. "He is committed to getting our economy back on track, upholding our country's rule of law and looking out for Arizona families."
Watch the ad: