Maryland’s transportation chief said Thursday he is negotiating daily with the companies building the Purple Line to try to keep them from quitting the project mid-construction over disputes about delays and cost overruns.

In a video briefing to the Montgomery County Council, Transportation Secretary Greg Slater provided few details of the conference calls, except to describe them as “very focused” and “very productive.” He said the office of Maryland Gov. Larry Hogan (R) is following the negotiations closely.

“We’re committed to resolving these issues and delivering the Purple Line to the citizens of Maryland,” Slater said.

A joint venture known as Purple Line Transit Constructors (PLTC) filed notice May 1 that it planned to terminate its contract to design and build the light-rail line because the $2 billion project was more than 2½ years behind schedule. It also said the state has refused to pay any of the $519 million it believes is needed to offset the delays and cover unanticipated costs.

The companies’ exit would result in abandoned construction sites in a 16-mile swath of the Maryland suburbs, where roads have been ripped up, rail overpasses are partially built over busy intersections and massive excavations are underway.

PLTC said it would leave the job in 60 to 90 days. However, project officials have since said that clock would not start until as late as June 20. That’s the deadline by which Purple Line Transit Partners, the group of companies overseeing the larger project as part of a 36-year public-private partnership with the state, must respond to its contractor.

The contractor’s notice has added deep uncertainty to Maryland’s largest transportation project, which has received national attention as one of the most far-reaching public-private partnerships of any U.S. transit project.

If the construction team walks off the job, the umbrella group would have to find other firms to finish the construction, which is likely to add significant time and potentially more costs. If the entire public-private partnership dissolves, the state would be left looking for a new way to complete and finance the project.

Asked what would happen if the state doesn’t reach an agreement with the contractor in June, Slater said Maryland officials have explored a “variety of scenarios” but remain focused on keeping the contractor on board.

Slater said state officials want to protect taxpayers from additional costs. He later added, “There’s a cost to our citizens for a project that’s stalled or delayed, and that’s very much on the table as part of our conversations as well.”

In an interview after the briefing, Slater said the contractor’s assessment of $519 million in cost overruns “is not in any way a representation” of the state’s view.

Maryland Transit Administrator Kevin Quinn said construction is about 30 percent complete and has continued “at a brisk pace.”

Quinn said the “goal” remains to open the Purple Line in two phases, beginning with six stations in Prince George’s County by late 2022 and opening the rest in Montgomery by mid-2023. Quinn’s assessment did not appear to include the 2½ years of delays that the contractor has raised, which would put the opening closer to mid-2025.

The line was initially scheduled to open in full in March 2022.

The east-west, 21-station Purple Line will be the Washington region’s first direct suburb-to-suburb rail line and will link Maryland’s spokes of the Metro system. Officials in Montgomery and Prince George’s have said they hope the line will attract economic development and provide a faster and more reliable alternative to buses.

The contractor has said delays stem from an unsuccessful lawsuit that prolonged the start of construction by a year, changes in CSX requirements for a crash wall along its tracks, new state requirements for the project’s embankments and culverts, and the state lagging in providing right of way.

A spokeswoman for PLTC referred questions after the briefing to the team’s initial written statement May 1. The contractor’s project manager said then the companies could not afford to absorb “hundreds of millions of dollars in additional costs that are [the state’s] responsibility.”

John Undeland, spokesman for the umbrella group, PLTP, released a statement saying, “We appreciate Secretary Slater’s and Administrator Quinn’s positive comments about our discussions and their commitment to reaching a fair and equitable outcome. We are in daily conversation with [the state] to reach an agreement that enables us to continue advancing the project without further delay.”

Montgomery County Council member Tom Hucker (D-District 5), chair of the panel’s transportation committee, said having companies abandon such a massive project would be unprecedented locally, especially after “years of inconvenience” for residents living with the construction.

“You know how important this project is to our whole region,” Hucker said. “. . . It would be appalling to see this get stalled this summer after three years of construction.”

Council member Evan Glass (D-At Large) said he was concerned about the state’s lack of “oversight and accountability” as potential costs and delays have mounted. He noted that Montgomery has contributed $225 million toward the line’s construction.

“Montgomery County taxpayers deserve to know how our funds are being used,” Glass said.