Reports on Friday that Flake would be launching his first ad led some in Arizona to speculate that Flake would go negative against Wil Cardon, the real estate mogul challenging Flake in the GOP primary for retiring Sen. Jon Kyl's (R-Ariz.) seat. Cardon has been climbing in the polls — thanks at least in part to millions of dollars of negative ads he's run attacking Flake.

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 FranksHarold (Trent) Trent FranksThe Hill's Morning Report - Lawsuits, investigations send Trump on Twitter tirade This week: Senate barrels toward showdown over Pompeo Arizona GOP tinkers with election rules with an eye on McCain's seat MORE (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: