PHOENIX  It looks like there will once again be Democrats on the Arizona Corporation Commission. But they may have failed in their bid to take control

The self-proclaimed “solar team’’ Sam George, Paul Newman and Sandra Kennedy bought advertising telling voters the way to ensure Arizona gets more solar-generated electricity is to put Democrats in control of the five-member panel. The other commissioners, both Republicans, are not up for election this year.

Preliminary results show Kennedy leading the pack, followed by Newman.

But the numbers were still too close to call to see who would cinch the third slot — and whether any of the three Republicans  Marian McClure, Bob Stump and Barry Wong  will be elected.

The divide between the camps was not that great, with the GOP contenders saying they also favor promoting solar energy.

The main difference between the two tickets was that the Republicans have said that solar alone cannot be relied on to provide for Arizona’s future power needs. They have instead promoted a mix which also includes the option of new nuclear power plants.

The last Democrat to serve on the commission was Renz Jennings who left after the 1998 election. And the Democrats lost the majority two years earlier.

Despite that, it was the allRepublican commission that imposed Arizona’s first-ever “environmental portfolio’’ mandate, which now requires that 15 percent of all power used in this state be generated from renewable sources like solar, wind and geothermal.

On paper, that does not spell out how much of that has to come from solar. But there is a requirement that 30 percent of the renewable energy comes from “distributed generation,’’ which primarily would consist of solar cells on the roofs of homes and businesses. George, however, pushed for a larger solar requirement given the state’s abundance of sunshine.

The issue of solar and other renewable sources has become a higher profile issue since the original commission action with the increasing public concern about climate change. Much of Arizona’s electricity comes from power plants fueled by coal and natural gas, both of which emit carbon dioxide which may contribute to global warming.

The flip side has been the acknowledgement that, at least for the time being, electricity generated by solar is more expensive than from other sources. That has resulted in the commission allowing the utilities to charge their customers more to make up at least part of the difference.

Supporters of solar, however, contend that the mandate to use more solar, not just here but elsewhere, eventually will drive down the cost. They also said the relatively low cost of fossil fuels does not take into account other factors like health effects.

Wong should have had a bit of a legup on the other candidates: He actually served on the panel for six months in 2006, filling out the term of a commissioner who resigned.

The race also could determine whether the commission continues to be populated solely with Maricopa County residents. McClure is from Tucson; Newman lives in Bisbee.

Incumbent Kris Mayes, who is not up for election this year, was officially a Maricopa County resident when she was appointed and when she ran for her own term. But Mayes said she reregistered for this election as a Yavapai County resident, where she grew up and where she said she spends some of her time.

Tucsonan Sharon Megdal was the last commissioner from outside the Phoenix metropolitan area. And she never actually was elected: She was appointed to fill a vacancy on the panel and lost her bid for a term of her own in 1986.

There have been several efforts to amend the constitution to require the commissioners to be elected by district, rather than at large, all of which have failed.