A veteran MBTA leader will soon end his tenure chairing the agency’s board, and a former co-chair of the Legislature’s Transportation Committee will step into the role at a pivotal point.

MBTA Board of Directors Chair Thomas Glynn, 78, plans to step down on Nov. 1, Gov. Maura Healey’s office announced Monday. The governor picked Thomas McGee, who also spent four years as mayor of Lynn, to succeed him in the leadership post.

McGee, a 23-year veteran of the Legislature, will lead the board during a stretch when the agency’s standing on Beacon Hill will be critical.

The T is draining its reserves to boost spending this fiscal year, and faces a budget shortfall of roughly $700 million in the next fiscal year that begins July 1. Officials project the MBTA could run out of cash in the first quarter of fiscal 2026 without additional assistance or major cuts that could undo progress in recent months toward improving service and restoring rider confidence.

While the new income surtax is generating new money for transportation, MBTA officials and the Healey administration have not indicated exactly how they plan to tackle the massive gap, though T General Manager Phil Eng has hinted the agency might need to seek additional state financial help. Healey created a task force to review the topic of transportation financing, and its report is due by the end of the year.

McGee, who will turn 69 in December, has been blunt during MBTA Board meetings about the outlook, criticizing “a substantial lack of investment” in the T and identifying sluggish growth in the state’s sales tax — a portion of which automatically goes to the MBTA — as a significant source of funding woes.

“Tom McGee understands the scope and the scale of the issue, and he knows the right folks to talk to up on Beacon Hill,” said Brian Kane, executive director of the independent MBTA Advisory Board that represents cities and towns who help fund the T.

McGee joined the agency’s board in 2023, but has been in state transportation policymaking circles for years. He joined the Legislature’s Transportation Committee in 2003, and was its Senate chair from 2011 to 2018 — a period that covered the disastrous winter of 2015 and creation of the T board’s predecessor.

In a statement, McGee said he looked forward to working with other Healey administration transportation officials “to deliver on our promise of a world-class public transportation system that we can all be proud of.”

Glynn for decades has been a central figure in state transportation policy and management. He served as general manager of the MBTA from April 1989 to April 1991 under former Gov. Michael Dukakis, and worked as CEO of Massport during the Patrick administration.

In a statement, Glynn said he’s “proud of the work that the MBTA Board has done these past couple of years” under Healey’s team.

“This Board showed up every day with the urgency necessary to meet the challenges facing the T, and we refused to settle for the status quo,” he said. “As a result, we’ve been able to deliver major improvements across the system and dramatically improve safety and reliability. I’m confident that the T will continue making important progress under the leadership of Tom McGee.”

Healey’s office said the governor would appoint a new member to bring the MBTA board back to full strength “in the near future.”

Officials are working to steady the MBTA after safety and reliability failures, which culminated in a blistering federal investigation in 2022. Riders have faced long stretches of disruption this year while crews repair tracks where trains can’t safely operate at normal speeds, and data show the agency is turning the corner.

Kane said the MBTA is “in a much better place today than it was when [Glynn] took over.”

“The governor made an inspired choice to appoint him to chair the board. I also think Tom McGee is a great successor. He’ll continue the great work,” Kane said. “Glynn was the GM of the T. He left in 1991. The fact that he came back 31 years later to help stabilize it is incredible. I’m sad to see him go. I’ve seen a lot of board chairs, and he’s probably been the best in recent memory.”

Healey praised Glynn for overseeing “a transformative period at the T,” noting improvements to safety and reliability.

“I’m proud to be appointing Tom McGee as the next Chair of the MBTA Board of Directors. As the former Mayor of a Gateway City and Senate Chairman of the Transportation Committee, he knows how critical our transportation infrastructure is for the communities in and around Boston, and across our entire state,” Healey said. “He has been a trusted and reliable voice on the MBTA Board, and I’m excited for the future of the T with his leadership.”