The chairman of Maine’s Public Utilities Commission has left his job, creating a void in an agency that is at the center of divisive issues including energy policy and power company rates.

Mark Vannoy resigned May 3. His six-year term had officially expired on March 31, but he stayed on an additional month before stepping down.

Gov.  Janet Mills has yet to nominate a replacement.

“The governor is in the process of reviewing candidates to succeed the outgoing chairman and intends to nominate an individual soon,” Lindsay Crete, the governor’s press secretary, said Tuesday. “She is committed to selecting an experienced and qualified leader who will uphold the PUC’s mission of ensuring that Maine citizens have access to safe and reliable utility services at just and reasonable rates.”

The PUC has three commissioners who serve staggered, six-year terms. They are nominated by the sitting governor, reviewed by the Legislature’s energy committee and confirmed by the Senate.

Vannoy was appointed by former Gov. Paul LePage in 2012. LePage made him chairman in 2015.

Mark Vannoy Press Herald file photo

Because LePage was in office for eight years, he had the opportunity to appoint all three commissioners. There has been much speculation in energy circles about whether Mills will shift the direction of PUC decisions by appointing a chair who’s likely to look more favorably on renewable energy and be tougher on utilities.

During his term, Vannoy focused on issues that included Maine’s higher-than-average electric rates and inadequate natural gas pipeline capacity. But he also came under fire from renewable energy advocates for decisions they saw as damaging the growth of the residential solar power market, such as reducing financial incentives for net metering.

Vannoy’s term expired on March 31. He remained at the helm, however, to deliberate the New England Clean Energy Connect case. In April, the commissioners voted 3-0 to approve a permit for Central Maine Power to build a transmission line through Maine to supply Canadian hydro power to Massachusetts.

Until Vannoy is replaced, the commission will operate with two members.

“The commission’s deliberations will continue as scheduled,” said Harry Lanphear, the agency’s spokesman. “The commission can function with two commissioners and has done so historically on many occasions.”

Lanphear said a 1-1 tie vote – if it were to occur – would not meet the legal standards for a decision. But he added that such an instance hasn’t happened in recent memory.

Vannoy is a civil engineer and was an associate vice president in the infrastructure and civil practice group at Wright Pierce in Topsham. He also served as an officer in the Navy.

The commission regulates more than 400 electric, telephone, water, and gas utility companies and districts. It sets rates, regulates service standards and monitors operations for safety and reliability, among other things. Like a court, it adjudicates cases and it may take testimony and  subpoena witnesses. It conducts investigations, such as an ongoing probe into Central Maine Power’s billing problems and customer complaints.