PHOENIX — The lone Democrat on the Arizona Corporation Commission is accusing its newest member of “using her office to advance her election chances.”

In a filing at the commission, Sandra Kennedy said that Lea Márquez Peterson appears more interested in pleasing Gov. Doug Ducey, who appointed her, and Don Brandt, the chief executive of the parent company of Arizona Public Service, than in getting answers from APS about what led to the heat-related death of a customer last year.

The move comes as Kennedy is pushing to force Brandt and other top corporate executives to come to the commission to answer questions, under oath, about APS policies and practices, particularly as they relate to when customers are disconnected. She already has the support of Commission Chairman Bob Burns for that move.

But Márquez Peterson told Capitol Media Services she’s not sure that’s appropriate — at least not yet. She instead continues to promote an outside probe of what happened, including the actions of the commission staff.

Only then would she consider bringing in someone from APS or parent company Pinnacle West Capital Corp. And she’s not sure it has to be Brandt.

Kennedy, for her part, said Márquez Peterson is loath to take that step “because she is beholden to Mr. Brandt and Pinnacle West for campaign contributions,” a clear reference to the money donated to her ill-fated 2018 congressional campaign. Márquez Peterson, tapped by Ducey to fill the vacancy created by the resignation of Andy Tobin, has to run in 2020 to keep her commission post.

“Perhaps Commissioner Márquez Peterson is worried about her own political future as a Republican without Don Brandt and Pinnacle West supporting her,” Kennedy said.

Kennedy also suggested that Márquez Peterson was acting in “seeming coordination” with the governor who appointed her, noting that Ducey last month accused the commission of “mission creep,” getting into areas beyond its clear constitutional authority to set rates.

But Márquez Peterson denied that the governor discussed his claim of “mission creep” when he interviewed and appointed her to the commission.

Márquez Peterson also dismissed Kennedy’s overall comments, made both in a formal filing at the commission and to Capitol Media Services, as a “political response” to her calls for an outside probe.

“I’m just really focused on responding to the public and the media who requested additional information and how we come up with policies to protect Arizona’s ratepayers,” Márquez Peterson said.

She suggested that there’s also politics behind Kennedy’s attack on her. She pointed out that Kennedy is campaign manager for Bill Mundell, one of the Democrats running for the three available slots on the commission on that 2020 ballot.

Burns is also questioning whether Márquez Peterson is playing politics and is loath to push too hard against APS.

“She was working with the state chamber, which has very strong ties to APS,” said Burns of Márquez Peterson, a former head of the Tucson Hispanic Chamber of Commerce. She backed the company’s successful effort to quash a 2018 initiative to force all utilities to generate more power from renewable sources. “The position she was in before she came to the commission would indicate that she has a connection with those folks,” Burns said.

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Now, said Burns, Márquez Peterson has a new position. “And where you sit depends on where you stand,” he said. “So we need to know where she stands.”

Questions remain as to whether Brandt will be subpoenaed, and whether there is now a working majority to force him to testify.

“I would support full disclosure as to the facts of the situation,” said Commissioner Boyd Dunn. But he said that doesn’t necessarily have to come from Brandt.

And Dunn, a former judge, said a more logical first step might be for commissioners to subpoena any documents they want, review those, and only then call in corporate executives to question them.

That’s also the position of Justin Olson, the remaining commission member.

“If we’re not getting the information that we need to provide ... proper oversight and a subpoena is needed, then that’s the action the commission should take in order to get that information.”

Márquez Peterson, on the job now for only about a month, said she hasn’t researched the issue of subpoenas. But she’s not ready to go there — at least not now.

“I think the first reasonable step is further investigation,” she sais.