Leaders in the Washington region on Wednesday removed Maryland Gov. Larry Hogan’s toll lanes plan for the Capital Beltway and Interstate 270 from a key list of long-term transportation projects, leaving it at greater risk of not securing federal environmental approval.

The move by members of the Washington Council of Government’s Transportation Planning Board came at the request of Montgomery County Executive Marc Elrich (D), a vocal critic of the Hogan-backed toll project. Elrich’s proposal drew support from almost every Maryland member present, as well as from some elected officials from the District and Northern Virginia.

“The governor has steamrolled this project through state government,” Montgomery County Council member Evan Glass (D-At Large), a planning board member, said after the vote. “But the regional leaders have said ‘not so fast.’ ”

The vote potentially is a major blow to Hogan’s signature transportation proposal, which aims to relieve traffic congestion by adding four toll lanes — two in each direction — on part of the Beltway and I-270. The project also would replace the American Legion Bridge with an expanded structure. The tolls would be priced to keep lanes moving at 45 mph or faster, while regular lanes would remain free.

Critics say that widening the highways would harm environmentally sensitive parkland and streams while bringing traffic closer to homes, schools and businesses.

The board struck the toll lanes proposal from a list of projects to be included in a required air-quality analysis of the region’s long-range transportation plan. The COG analyzes the collective vehicle ozone emissions that would be produced by the projects to ensure they would abide by federal limits on air pollution.

A project also must be part of a region’s long-range plan before it can secure the federal environmental approval that is required before construction, according to a spokeswoman for the Maryland Department of Transportation. Wednesday’s vote “effectively removes” the toll lanes proposal from the latest update to that plan, according to COG staff.

MDOT spokeswoman Erin Henson called the board’s action “a vote against” easing congestion across the American Legion Bridge, providing reliable bus service, improving the state’s infrastructure and creating “thousands of jobs.” It also was a “vote against” private investment in the state’s transportation network, she wrote in an email, referring to Maryland’s proposal to build the lanes via a 50-year public-private partnership.

“Maryland is not prepared to give up on any of that and will continue to work toward solutions that will provide congestion relief in the National Capital Region for today and for generations to come,” Henson wrote.

MDOT recently selected the Australian firms Transurban and Macquarie to develop the state’s toll lane proposal and had planned to seek approval of a “predevelopment agreement” with the companies as early as next month. MDOT’s selection also remains under protest by a losing bid team that argues that the winning proposal was based on unrealistically low construction costs.

Asked whether the regional board’s action would affect the timing of that contract, Henson wrote, “The solicitation and the environmental review are two separate processes.”

A spokesman for Hogan (R) did not respond to a request for comment.

It is unclear what effect the board’s vote will have on replacing the American Legion Bridge with an expanded structure, a proposal that has far broader political support.

After the meeting, Elrich said traffic congestion could be sufficiently relieved by adding two rush-hour reversible lanes to each highway. He said he thought two lanes would fit within both highways’ rights of way, which would reduce the potential effects on surrounding parkland and neighborhoods. They also might not require tolls if the state financed the lanes itself, he said.

“This is a big deal in terms of them having to rethink their plans,” Elrich said of the Hogan administration after the vote. “If they do it as two reversible lanes, this becomes a whole lot easier.”

Speaking in favor of striking the four-lane proposal from the regional plan, Rockville Mayor Bridget Newton told fellow board members that nine Rockville neighborhoods would be “terribly impacted” by a widening of I-270.

“This is not ready for prime time,” Newton said. “This project does nothing to move our region forward — not in social justice, not in environmental justice, and it’s not the way we should be going.”

Those arguments won support from some elected leaders beyond Maryland.

Arlington County Board member Christian Dorsey (D) said he objected because the proposal “seems nowhere close” to having broad state and local consensus.

A representative of the Virginia Department of Transportation argued for keeping the Maryland toll lanes in the regional plan, saying they are needed to connect to express toll lanes in Northern Virginia and relieve the bottleneck at the American Legion Bridge. Transurban operates more than 50 miles of toll lanes in Northern Virginia and is working to extend Virginia’s Beltway toll lanes to the bridge.

A representative of the D.C. Department of Transportation abstained from voting on whether to remove the toll lanes project.

Glass and some other toll lane critics said the proposal would need to include more mass transit and less environmentally damaging pavement to win their support. But some proponents said there’s still time to restore the proposal to the long-range regional plan before that plan is approved next year.

“It’s absolutely a setback,” said Jason Stanford of the Northern Virginia Transportation Alliance. “I’d rather they have not done it, but I still think there’s a path forward on the project.”

Kelly Russell, an alderman in the city of Frederick, said the toll lanes would provide better mass transit for residents in her outer suburb because commuter buses would use the lanes free. Frederick won’t get expanded MARC commuter rail anytime soon, she said.

“Our option is commuter bus,” Russell said. “The only way to move consistently dependable commuter buses is with these toll lanes.”

The board also voted to make the reduction of greenhouse gas emissions a bigger focus when updating the long-range transportation plan in the future.