Maricopa County Sheriff Joe Arpaio has endorsed Arizona Attorney General Tom Horne's re-election campaign.

The sheriff said Tuesday that he endorsed Horne because he's impressed with his record as attorney general, particular his efforts to confront illegal immigration.

Horne faces former Arizona Department of Gaming director Mark Brnovich in the GOP primary.

Arpaio said he won't join others in criticizing Horne for campaign complaints that were filed against him.

Horne is appealing a complaint in which he and an aide were accused of illegally coordinating outside campaign spending in his 2010 election bid.

He has denied wrongdoing.

In separate complaint, a former employee alleges Horne used his office staff to do work on his re-election campaign.

Horne said the employee has a history of making false claims against her employers.