BOSTON (AP) — The general manager of Boston’s troubled public transit system, who shepherded the agency through the pandemic when ridership plummeted and has faced calls to resign during a federal safety review, announced Tuesday that he will step down early next year.

Steve Poftak in a letter to employees of the Massachusetts Bay Transportation Authority said that his last day on the job will be Jan. 3, just days before a new governor is sworn in.

“Serving as MBTA General Manager has been the experience of a lifetime and it has been my honor and privilege to work with all of you,” he wrote. “While we have faced and will continue to face challenges, I believe in the strength and resilience of the MBTA. As I look back on my four years as General Manager, I take great pride in what we have accomplished together.”

The letter did not say what his plans were.

Poftak, who was appointed to the MBTA’s fiscal control board in 2015 by Republican Gov. Charlie Baker, took over as general manager in December 2018 from Luis Ramirez, who spent just 15 months on the job. Baker’s term ends in January and he is not seeking reelection.

Ridership dropped when businesses moved to remote work during the pandemic. As of May 2020, bus ridership was at about 20% of pre-pandemic levels and weekday subway ridership dropped to 8% of pre-pandemic levels.

The subway system, the nation’s oldest, experienced a series of safety problems in the past year or so that prompted a review by the Federal Transit Administration.

The FTA, in a highly critical report in June, issued four “special directives,” requiring 53 separate actions that the agency was required to take, including addressing worker shortages, prioritization of safety management, safety communication, and operating conditions, policies, procedures and training.

Poftak in his Tuesday letter acknowledged problems, but also touted improvements the system has made under his leadership, including the investment of billions of dollars in modernizing the bus fleet and commuter rail infrastructure.

“And while we know we have more work to do on safety, we have made great strides as an organization, building staffing, expertise, and above all, commitment to making the system as safe as it can be,” he wrote.