Here’s how. Trump elevated Cheryl A. LaFleur to the chairmanship of the Federal Energy Regulatory Commission. As a result, the sitting chairman Norman C. Bay, rather than remain an ordinary commission member, resigned effective Friday.

That wasn’t part of the plan. When Bay departs, the five-person commission, which already has two vacancies, will no longer have a quorum. No quorum means no approvals for contested issues including electric transmission lines, natural gas pipelines and utility plans. Any new member nominated by Trump must go through Senate confirmation, something that could take another four months.

“This leaves FERC paralyzed for the time being,” said Arvin R. Ganesan, vice president for federal policy at Advanced Energy Economy, a business advocacy group. The commission issues an average of more than five orders a day, according to a former member who counted them.

The looming lack of a quorum “has increased the urgency” for project approvals this week, but that seems unlikely, according to Capital Alpha Partners, a firm that provides policy research to financial institutions, In a note to clients, it said that some of the pipelines in line for approval “may face in-service delays of up to a year due to seasonal prohibitions on tree-clearing to mitigate impacts on migratory birds, bats, and other species.”

FERC, an independent agency, regulates interstate oil and gas pipelines, electricity transmission lines, liquefied natural gas terminals, hydropower projects and wholesale electricity prices.

The natural gas pipelines waiting for approval include Williams Partners’ Atlantic Sunrise to carry Pennsylvania shale gas to eastern markets; a Nexus pipeline linking eastern Ohio to southern Michigan; Rover, which will carry gas from western Pennsylvania, West Virginia and eastern Ohio to southern Michigan; and Atlantic Coast, which travels from West Virginia to North Carolina.

Some of those pipelines have been waiting for a long time, but are still resolving issues. Atlantic Coast made at least three additional filings to the FERC in January, covering migratory birds, visual impact and route adjustments.

Pipeline opponents are also rushing to get rulings this week. Sens. Edward J. Markey, D-Mass., and Elizabeth Warren, D-Mass., urged the commission to quickly rescind an order authorizing Spectra’s Atlantic Bridge pipeline. They have charged that Spectra has potential conflicts of interest with a contractor.

FERC can continue to make rulings as long as they aren’t contested. But contested issues are common as issues are raised not only by environmentalists but also by competitors or people living along a project route. The commission is looking at ways to delegate more power to its staff, but that might be a violation of its own statutory authority.

The idea of reshuffling the commission before filling the empty seats originated with the energy transition team, a group close to the utility and oil and gas industries. The suggestion traveled up through the administration until it landed on Trump’s desk. Elevating LaFleur required his signature.

Sources close to the transition and administration say that the idea was to elevate LaFleur because, while nominated by President Barack Obama, she has more than 20 years of experience working in the utility business. Bay, while well liked even by those in the utility business, has a long record as a prosecutor and director of FERC’s enforcement division.

The other member of the commission is Colette D. Honorable, also an Obama appointee.

Trump will get to fill all three empty seats with Republicans.