President Trump could use his pardon power for the first time next week if he announces at his Phoenix campaign rally that he’ll wipe away former Maricopa County Sheriff Joe Arpaio’s criminal record.

But the pardon, if Trump decides to issue it, would be highly unorthodox and break with the Justice Department’s guidelines for clemency, according to legal experts.

“I am seriously considering a pardon for Sheriff Arpaio,” Trump told Fox News in a recent interview of the six-term sheriff who built a national profile for himself by cracking down on unauthorized immigrants. “He has done a lot in the fight against illegal immigration. He’s a great American patriot, and I hate to see what has happened to him.”

Trump could issue the pardon as early as Tuesday, Fox News reported, when he’s appearing at a campaign rally in Phoenix. Arpaio warmed up crowds for Trump on the election trail, boosting his vow to build a wall on the U.S.-Mexico border and deport unauthorized immigrants. Arpaio, 85, told NPR he’d be honored to receive the pardon.