Maryland Gov. Larry Hogan (R) has delayed a vote scheduled for next week on his plan to add toll lanes to the Capital Beltway and Interstate 270 until the state treasurer, who has said she has “serious questions” about it, is in town to vote, a Hogan spokesman said Friday.

The governor’s office and Comptroller Peter Franchot (D) had come under criticism since reports Wednesday that Hogan would pursue a vote May 8 by the Board of Public Works, even though Treasurer Nancy K. Kopp (D), one of its three members, had said six months ago that she would be out of the country.

The board — comprising the governor, comptroller and treasurer — was scheduled to vote on Hogan’s request to designate the project as a public-private partnership. That would allow the state to begin soliciting proposals from teams of companies.

Hogan spokesman Michael Ricci said Friday that the governor’s office decided to delay the vote after consulting with the comptroller’s office. Ricci previously had said that Kopp could appoint someone to vote in her place and that the toll plan was too critical to hold off on voting until a May 22 meeting, as Kopp had requested.

“Marylanders continue to sit in soul-crushing traffic, including an average of seven hours of congestion on I-270 and 10 hours of congestion on I-495,” Ricci said in an email Friday. “Every single day that goes by without action destroys quality of life for hundreds of thousands of Marylanders and their families.”

Critics, including environmental groups and lawmakers from Montgomery and Prince George’s counties, had said the Board of Public Works shouldn’t vote on such a massive and long-term highway project without all three members. Kopp, who is elected by the General Assembly as a fiscal watchdog, said she had told the Maryland Department of Transportation (MDOT) that she had numerous questions about the proposal’s environmental and financial effects.

The project could result in five 50-year state contracts, together worth more than $11 billion.

The board is expected to vote on the solicitation proposal in June, when all three members are present. Hogan will be absent from the May 22 meeting, Ricci said. Any public-private partnership agreements reached by the state would have to come back to the board for approval before any contracts could be signed.

Kopp said Friday that she appreciated the governor delaying the vote “to allow ongoing discussion and consideration.”

“There are a great number of serious questions on this project — an infrastructure project that will cost billions of dollars and last more than half a century,” Kopp said. “I continue to believe that the range of options, with their long-term financial and environmental impacts, should be carefully examined and discussed, with meaningful input from the public and their elected local governments.”

Activists opposed to highway expansion have begun to focus on trying to persuade Franchot to oppose Hogan’s toll lane plan.

Franchot’s spokesman, Alan Brody, declined to comment Friday on the proposal, saying the comptroller’s office doesn’t publicly discuss issues that will come before the board.

However, Franchot’s office tweeted Friday: “Many have contacted me concerning the Board of Public Works’ scheduled vote on the Capital Beltway and I-270 Highway Expansion proposal. I support the decision to postpone the vote, and continue to welcome input and opinions on this proposal.”

Hogan has said that adding up to four toll lanes each to I-270 and Maryland’s portion of the Beltway is the only way the state can afford to relieve severe traffic congestion. In what he has said would be the largest public-private partnership in the United States, companies would pay to design and build the lanes in exchange for keeping most of the toll revenue long-term. Hogan has said the lanes would cost the state nothing.

Critics say that expanding highways only brings more traffic and that the state should complete a federally required study of the potential environmental impacts before soliciting any public-private partnerships.

So far, the study has found that adding toll lanes could require destroying up to 34 homes along the Beltway and taking strips of backyards, parkland and other land from 1,500 property owners along both highways.

Maryland Sierra Club Director Josh Tulkin, who met with Franchot on Friday, said the vote delay should result in more scrutiny.

“The governor, comptroller and treasurer should use this extra time to demand more rigorous analysis from MDOT,” Tulkin said.

In a letter to the Board of Public Works dated Friday, 40 state lawmakers representing areas along the Beltway and I-270 in Montgomery and Prince George’s counties asked for a completed environmental review, “detailed analysis of the costs and financial risks,” and a projection of the toll prices before the state is allowed to solicit private partners.

“There is great uncertainty involved for the state, taxpayers, and individual motorists in acting without full information on the choices for traffic relief in Maryland,” the letter said.

John Townsend, spokesman for AAA Mid-Atlantic, said it would have been “bad optics” to hold the vote without Kopp, but he’s concerned about any delays on a project that he believes would bring “desperately needed” traffic relief.

He said Maryland needs to stay economically competitive with Northern Virginia, where motorists in both the tolled and free lanes have found congestion relief since the state added toll lanes to its portion of the Beltway and other highways.

“We’re literally choking on traffic congestion,” Townsend said. Maryland is “losing its competitive edge to Northern Virginia and sending the wrong signal to the business community. My fear is that suburban Maryland is going to end up a bedroom community.”