President Trump's choice to serve as the head of the nation's top energy watchdog said Thursday evening that the last six months when the agency was forced to close for lack of members was a never-before-seen occurrence.

"The absence of a quorum was unprecedented," said Neil Chatterjee, the newly appointed chairman of the Federal Energy Regulatory Commission, in a statement. Trump appointed him earlier on Thursday to serve as chairman of the commission even though he was unanimously confirmed by the Senate last week to serve as a commissioner.

FERC lost most of its members six months ago after Trump picked veteran commissioner Cheryl LaFleur to serve as acting chairwoman. That was immediately followed by the former Democratic chairman, Norman Bay, resigning, leaving only two members to remain on the commission. FERC requires at least three commissioners to function.

It was the first time the independent agency was forced to close in its 40 years of service. Chatterjee praised Lafleur, who he said "rose to the challenge and created stability" during an uncertain time.

The White House named Chatterjee to the chairmanship Thursday soon after Republican commissioner Robert Powelson was sworn in to restore the quorum.

Up until a few days ago, LaFleur was the only member on the commission, which has the heavy lift of regulating the nation's wholesale electric grid while permitting interstate natural gas pipelines and related infrastructure.

"I want to thank Chairman LaFleur for the tremendous work she's done in guiding the agency," Chatterjee added. "I look forward to working with Commissioner LaFleur and Commissioner Powelson on behalf of the American people. And I hope that we will have all five Commissioners here soon with the confirmation of Kevin McIntyre and Rich Glick."

FERC, at full strength, is a five-member panel of equal Republican and Democratic commissioners, with the chairman historically sharing the same party with the president. Chatterjee is a temporary hold on the chairmanship until Trump's preferred nominee is confirmed by the Senate. Trump has nominated McIntyre to serve as chairman once he is confirmed sometime in the fall. Glick will join LaFleur as the number-two Democrat on the commission.

"I am honored that President Trump has designated me as Chairman of the Commission until Kevin McIntyre is confirmed, and I am eager to take on this responsibility," Chatterjee said.