Sens. John McCainJohn McCainBush biographer: Trump has moved the goalpost for civilized society White House to pressure McConnell on ObamaCare McCain: Trump needs to state difference between bigots and those fighting hate MORE (R-Ariz.) and Jon Kyl (R-Ariz.) endorsed Rep. Jeff FlakeJeff FlakeOPINION: Congress should censure Trump for his unfit conduct Club for Growth endorses Nicholson in Wisconsin GOP primary Immigration battlefield widens for Trump, GOP MORE's (R-Ariz.) Senate bid on Friday.

They also blasted his primary opponent, businessman Wil Cardon (R), for misrepresenting Flake's record.

McCain and Kyl described Cardon's "mis-characterizations" as "reckless" at a news conference, according to the Arizona Daily News.

"The effect of the Wil Cardon campaign in the primary is not to elect Wil Cardon," said Kyl, who is retiring and Flake is running to replace. "He hasn't been able establish why he should be elected but he tears Jeff Flake down."

McCain said he was "disturbed" by the kind of campaign being run by Cardon and warned that they could hurt him in the general election against former U.S. Surgeon General Richard Carmona (D).

"Frankly, I also worry that these attacks might make it harder in the general election for us to elect Mr. Jeff Flake to the United States Senate," McCain said.

Flake has had to work harder than expected to beat back Cardon, who has attacked his record on immigration in a strongly negative campaign. Cardon, a wealthy businessman, has poured his own money into the race.

Carmona's campaign was quick to point out that both McCain and Kyl praised the former surgeon general and backed his appointment to the position during the President George W. Bush administration — McCain went so far as to call him an "exceptional man."

Arizona's Senate primary is Aug. 28.