Maryland Gov. Larry Hogan has secured key support on a deal that would put a multibillion-dollar project to build toll lanes on the Beltway and Interstate 270 back on track, the governor’s office announced Friday.

The deal would advance an initial phase of the project involving the American Legion Bridge, a western stretch of the Beltway and the lower section of I-270. It also underscores that the state will not acquire properties lying in the path of the proposed new lanes until building of the lanes has been approved, and it includes earlier funding for transit in Prince George’s and Montgomery counties.

The highway project would be one of the nation’s largest public-private partnerships.

In June, an initial version of the plan won approval from the state’s Board of Public Works, which approves contracts. But the effort hit a snag when Comptroller Peter Franchot (D), who sits with Hogan on the three-member board, expressed concerns about potential changes that could have meant undertaking both highway projects simultaneously.

The new deal secures continued support by Franchot, the swing vote on the board, before a board vote set for Wednesday.

“As a result of our ongoing and constructive dialogue, the residents, commuters and employers of the region will benefit from a much better project,” Franchot said in a statement. “One with better roads, better mass transit, good-paying jobs and a true partnership between our state and local governments.”

Hogan (R), whose administration conceived of the plan, said in a statement that the deal means Maryland can “solve what has been the number one problem in the Washington Capital Region for decades.”

“With this plan, no one will be required to pay any tolls, all existing lanes will remain free, and billions of dollars in road improvements will be made without any new taxes,” Hogan said.

The vote Wednesday will fall on the opening day of this year’s General Assembly session. That timing is important to Hogan because opponents of the toll lane proposal are planning legislation that could slow it or stop it.

The plan involves private companies building up to four toll lanes on the Beltway and I-270, financing their construction and keeping most of the toll revenue long-term. The state transportation department would pay nothing, officials say. The tolls would fluctuate in response to traffic volume to keep vehicles moving. Existing lanes, which would be rebuilt, would remain free. In all, the contracts could be worth more than $11 billion, officials say.

Under the amendments agreed to by Hogan and Franchot, the state would first solicit a builder to widen the American Legion Bridge between Maryland and Virginia, as well as the Beltway up to I-270 and the section of I-270 that stretches to I-370 in the Shady Grove area of Rockville.

Officials aim to finalize the contracts for that first section by spring 2021.

Changes to the remaining sections of the Beltway in Maryland would come later, contingent on further approvals by the Board of Public Works.

The new arrangement delays work on a contentious section of the Beltway between I-270 and Interstate 95, which could require the destruction of dozens of homes.

The deal makes clear that the state agencies managing the plan will not acquire any properties until the agreement with the builder has received final approval from the board. Franchot said a side deal will guarantee the projects are undertaken using union labor.

The agreement also significantly revises the way in which transit services in Prince George’s and Montgomery County would benefit from the highway project. The previous plan would have set aside 10 percent of toll revenue for transit, but only after the contractors had recouped construction costs, which could have taken many years.

Now, the state would be required to reach formal agreements with the counties to ensure their transit systems benefit, a provision that officials said will lead to money coming in sooner and will give local leaders a chance to play a role in determining the terms of the payments.

The board had last been scheduled to vote on the project in December, but Hogan canceled the meeting when it was clear he lacked Franchot’s support. State Treasurer Nancy Kopp, a Democrat who represents the General Assembly on the board, previously voted against the highway program. She could not be reached for comment Friday.

Incoming transportation secretary Greg Slater had previously said the state would pursue a phased approach. But the deal announced Friday involved other concessions, too.

Slater, the former state highways chief, said Friday that the breakthrough came when the parties focused on the sections of road “where we have more consensus.”

But he said that does not mean users of the other sections of the Beltway should not expect ultimately to see benefits, too.

“This is the area that we’re going to start because we have that consensus,” Slater said. “That doesn’t mean we don’t want to provide congestion relief elsewhere.”

The highway plan and a related agreement with Virginia to overhaul the American Legion Bridge, a notorious choke point, are two of Hogan’s signature transportation initiatives, projects that he says are vital to improve the flow of traffic around Washington.

But opponents of the plan have criticized it as tying the region’s future to cars and trucks that pollute. They have questioned the speed with which the huge plan has been put together and whether it will truly come at no cost to taxpayers.

The chairman of the Montgomery County Council transportation committee said he was glad that Hogan had agreed to changes to the plan but was critical of a process that he said was insufficiently transparent.

“The process is still lousy,” said Tom Hucker (D), the committee chairman, who has organized rallies seeking changes in the project. “Two people on a three-member Board of Public Works should really not be determining the fate of $11 billion, a commitment that our kids and grandkids could be stuck paying for.”

Nonetheless, Hucker said that deferring the second portion of the work on the Beltway and giving the counties a formal role in negotiations over transit funding were “two major improvements over the plan as it existed yesterday.”

Katherine Shaver contributed to this report.