U.S. Sen. Tim Kaine (D-VA) has written Chairman Kevin McIntyre asking that FERC grant rehearing requests on the Appalachia-to-Southeast Atlantic Coast (ACP) and Mountain Valley pipeline (MVP) projects.

In a letter, which was sent to the Federal Energy Regulatory Commission on Friday, Kaine expressed his concern over FERC’s rare 2-1 split decision in October that approved both projects. At the time, McIntyre, a Republican, and Richard Glick, a Democrat, had not yet been sworn in.

“Given that the Commission now has a full complement of five members, there is a real concern about whether the divided rulings by a partial Commission fairly reflect the FERC position,” Kaine wrote. He noted that nearly all of FERC’s 2016 decisions were unanimous.

About a month after Commissioner Cheryl LaFleur, who at the time was FERC’s lone Democrat, dissented from Commissioners Neil Chatterjee and Robert Powelson, dozens of groups and individuals filed rehearing requests challenging the projects’ certificate orders. LaFleur argued in part that the two pipelines should be merged into one to reduce environmental impacts.

Kaine’s letter supports those formal requests, some of them filed by environmental groups that are vehemently opposed to all natural gas infrastructure projects. The Sierra Club, which has filed for rehearing, welcomed Kaine’s letter on Monday, saying in a statement that he knows the Commission “should be a watchdog for Americans, not a rubber stamp” for the oil and gas industry.

But the senator stressed that he does “not endorse or oppose” the views of the petitioners on the “substantive merits of these projects,” saying instead that “it is important for the public to have confidence in the integrity of FERC’s process. All I request is for every step of that process to be followed to the fullest extent of the law.”

ACP spokesman Aaron Ruby said the project’s backers agree with Kaine that the Commission should completely follow its process, but said “we believe FERC has done so.” He added that “the law requires a quorum of three Commissioners to make permitting decisions, and FERC had such a quorum when it approved the ACP.” Ruby said ACP sponsors are confident that FERC will affirm approval of the project as it considers the rehearing requests.

As FERC continued to receive a steady stream of rehearing filings for natural gas pipeline projects, it tolled many of them to freeze the statutory timeframe in which it has to consider and decide on them. While Kaine acknowledged FERC’s announcement last month that it would review the decades-old policy that informs its pipeline certification process, he asked McIntyre for a “fuller understanding” of the orders. Kaine expressed concern over pipeline opponents claims that the tolling orders are being used to freeze appeals and advance construction.

The 303-mile, 2 million Dth/d MVP is targeting a 4Q2018 in-service date. It is a joint venture (JV) between EQT Midstream Partners LP, NextEra US Gas Assets LLC, Con Edison Transmission Inc., WGL Midstream and RGC Midstream LLC. MVP could not be reached to comment on Monday.

The 600-mile, 1.5 Bcf/d ACP is targeting a 2019 in-service date. The project is a JV of Dominion Energy Inc., Duke Energy, Piedmont Natural Gas and Southern Company Gas.

Both MVP and ACP are designed to deliver Marcellus and Utica shale gas to Southeast markets. Each greenfield project would start in West Virginia before crossing into Virginia to connect with the Transcontinental Gas Pipe Line. ACP would extend into North Carolina as well.