PHOENIX — Calling it a “stunning power grab,” Attorney General Tom Horne wants a judge to block a decision by the Citizens Clean Elections Commission to investigate whether he has been using his office for campaigning.

Horne’s attorney, Timothy La Sota, contends the commission lacks legal authority over anything Horne is doing because he is seeking re-election using private donations. La Sota said the commission can police the activities of only those who have accepted public dollars for their campaigns.

But Tom Collins, the commission’s executive director, said when voters created the commission in 1998 they did more than simply authorize them to give out public funds. He said they also gave the panel authority to police campaign finance violations by all candidates.

The next move is up to Maricopa County Superior Court Judge Dawn Bergin. She has scheduled a hearing on Friday.

Even if Horne succeeds in convincing Bergin the commission’s authority is limited, he is not out of the political woods. Even La Sota concedes the Secretary of State’s Office has authority to review complaints like the one filed by former Horne staffer Sarah Beattie.

But Collins pointed out the Secretary of State inquiry can only lead to a recommendation to pursue a full-blown probe, a recommendation that, by law, goes to the Attorney General’s Office.

And while a Horne aide is virtually certain to farm that out to a county attorney, presumably a Republican, that still leaves the possibility of political mischief: GOP elected officials are deciding whether to line up behind Horne’s re-election bid or support a primary challenge by Mark Brnovich.

And there’s another factor at work.

The maximum penalty that can be levied through an investigation that starts with the Secretary of State’s Office is a fine equal to three times the amount of money misspent. By contrast, the commission, should it find Horne violated the law, also has the option of tossing him from office.

Central to the issue is Beattie’s complaint she and others within Horne’s office, including Horne himself, routinely did work on his bid for a second term as attorney general. Those allegations, if true, would mean Horne used public resources for expenses that should have been done with campaign dollars.

La Sota, in his lawsuit, calls Beattie’s complaint “completely without merit.” And he said even if something she said is truthful, the conduct is “water cooler talk (about the campaign) that occurs in any office.”

But La Sota is hoping to short-circuit the Clean Elections probe before he has to prove any of that, saying the commission’s sole power — including removal from office — is only over those who have taken public funds.

“That’s not what the act says,” Collins responded. “He is taking a sentence out of the act, taking it out of context, and twisting it around to say something it doesn’t say.”

Collins said one reason the commission has parallel authority with the Secretary of State’s Office to investigate campaign finance allegations is because the commission has “tools” to expedite its investigation, including the ability to subpoena documents and compel testimony under oath. Horne has already been found in a separate investigation to have violated campaign finance rules for his 2010 campaign, and ordered to refund more than $400,000 in contributions. He has appealed that decision.