Rep. Jeff Flake (R-Ariz.) holds a commanding lead over businessman Wil Cardon in the GOP primary for Arizona’s open Senate seat, a new poll showed.

Flake takes 56 percent to Cardon’s 7 percent in the race to replace retiring Sen. Jon Kyl (R-Ariz.). Flake also holds a 56 percent approval rating among GOP primary voters in his home state, while Cardon remains unknown to 83 percent of voters.

Flake does best among supporters of Rick Santorum in the survey from Democratic firm Public Policy Polling. He takes 72 percent of Santorum supporters, compared to 58 percent of Mitt Romney supporters and 51 percent of Ron Paul supporters.

One interesting tidbit buried deep in the poll was that an endorsement from Maricopa County Sheriff Joe Arpaio now goes further for Arizona politicians than one from Sen. John McCain (R-Ariz.). Thirty-two percent of GOP voters said an endorsement from the man who calls himself “America’s toughest sheriff” would make them more likely to vote for a candidate, compared to 15 percent for McCain and 25 percent for Arizona Gov. Jan Brewer (R).

The poll of 412 likely GOP primary voters was conducted Feb. 17-19 using automated telephone interviews. The margin of error was plus or minus 4.8 percentage points.