Federal regulators hit the brakes Tuesday on a request to speed up construction of a portion of the Mountain Valley Pipeline, throwing another wrench into the problematic project.

The Federal Energy Regulatory Commission deadlocked 2-2 on Mountain Valley’s request to bore under streams and wetlands along the pipeline’s first 77 miles in West Virginia.

After running into legal problems with a permitting process that would have allowed digging trenches through water bodies, the company asked FERC to authorize an alternative method of drilling a tunnel below some of the streams and wetlands through which the pipe would pass.

Approval by the commission would have enabled Mountain Valley to put the first 77 miles of the pipeline into service while work on the remaining 226 miles — including a stretch through the New River and Roanoke valleys — is slowed by legal attacks from environmental groups.

But at FERC’s virtual meeting Tuesday, an order approving the boring request failed to get a majority vote. With the panel split 2-2, and the fifth commissioner abstaining from voting, the matter essentially died unresolved.

“It’s a significant setback” for Mountain Valley, said Gillian Giannetti, a staff attorney for the Natural Resources Defense Council.

“MVP is in a holding pattern, and there’s no clear end in sight,” she said.