Rep. Jeff Flake (R-Ariz.) goes to bat for Sen. John McCain (R-Ariz.) and goes after McCain's primary opponent, former Rep. J.D. Hayworth (R-Ariz.), in a new 60-second radio ad.

In the ad, Flake says McCain deserves the "lion's share" of credit for putting Congress on the brink of banning earmarks. He also says Hayworth (whom Flake doesn't refer to by name, but rather as McCain's "opponent") lost his way on the issue when he was in Congress.

In a direct shot at Hayworth, Flake also suggests that the former congressman lost reelection in 2006 because of that issue.

"Republicans including Sen. McCain's opponent lost their bearings on spending," Flake says. "They loaded up bills with pork barrel projects, and the voters punished Republicans by putting Democrats in charge."

It's a notable attack, given that Flake and Hayworth were colleagues.