BOSTON (SHNS) – Transportation Secretary Stephanie Pollack will depart Gov. Charlie Baker’s cabinet next week after six years as one of the most visible secretaries for a leadership role at the Federal Highway Administration, a decision that Baker called “incredibly bittersweet.”

Pollack will step down Tuesday to become FHA deputy administrator, Baker’s office announced Thursday morning. Registrar of Motor Vehicles Jamey Tesler will take over as acting transportation secretary, and RMV deputy registrar and chief operating officer Colleen Ogilvie will rise to the role of acting registrar.

Pollack’s departure shakes up Baker’s inner circle, and comes as travel patterns and transit budgets have been upended by the pandemic, the MBTA is cutting service, and the state continues to pursue major projects such as a South Station expansion, replacement of the Cape Cod bridges, and an Allston highway megaproject.

Baker said Thursday that Pollack did a “terrific job” at what was “in many respects one of the most difficult jobs anybody faced coming into our administration.”

“Before she joined the administration I met her when somebody suggested that I should interview her for the job. Neither one of us thought that was gonna go particularly well and we were both really surprised when it did. I think she’s done a terrific job under enormously difficult circumstances,” Baker said.

The governor pointed out Pollack’s deep understanding of the state’s transportation landscape and pointed out that in her new role she could influence the future of projects that are important to Massachusetts.

“Stephanie is going to play this as a public servant, because that’s kind of in her DNA, so the idea that she would walk in there and try and treat Massachusetts profoundly differently than she treats anybody else, that’s not going to happen,” the governor said. He later added, “It just never hurts to have relationships with people in high places.”

Pollack joined the Baker administration in January 2015 from Northeastern University’s Dukakis Center for Urban and Regional Policy, where she had built a reputation as a knowledgeable and vocal transportation expert who advocated for increased public transit funding.

Her tenure brought stability to a role that had been marked by turnover. Baker’s predecessor, Gov. Deval Patrick, cycled through four permanent transportation secretaries over his two terms: Bernard Cohen, James Aloisi, Jeffrey Mullan and Richard Davey, followed by a short stint with Frank DePaola as acting secretary.

“The Governor and Lt. Governor have my deepest gratitude for entrusting me with the stewardship of MassDOT and their leadership as transportation champions,” Pollack said in a statement on Thursday. “Massachusetts has become a leader in delivering a transportation system that puts people first and provides them with safer and better choices for walking, biking, using transit, or driving and I am confident that Jamey will be able to continue that good work.”

While leading MassDOT, the department has significantly increased its capital spending on the MBTA, a point that draws frequent praise from Baker.

“Throughout her career, Secretary Pollack has partnered with our organization to improve the quality of life and economic opportunities found in Massachusetts,” said Rick Dimino, CEO of the business group A Better City, in a statement. “We know she will continue to operate as a tireless, dedicated leader focused on building back better for the people of this country and meeting our climate impact goals.”

Pollack has also been front and center of the administration’s response to several high-profile crises.

She started during the disastrous winter of 2015, when record snowfall prompted multiple MBTA service shutdowns and creation of a new oversight board. In the summer of 2019, lawmakers started a probe into the Registry of Motor Vehicles after it failed to suspend the license of a driver later involved in a deadly crash. That winter, an independent panel concluded the MBTA did not sufficiently prioritize safety culture.

Some activists aimed criticism at Pollack — and the Baker administration as a whole — upon her departure, arguing that MassDOT under their watch has not done enough to address worst-in-the-nation congestion or an aging public transit system.

“The outgoing Transportation Secretary has presided over avoidable cuts to the MBTA and unproductive machinations to shape the Allston I-90 Multimodal project into a highway-first project,” the group TransitMatters said. “Numerous priorities such as the Rail Transformation Process and low-income fares also saw little progress since they were adopted by the FMCB. We hope that we may now enter a new period of collaboration that will support a strong, equitable and sustainable post-COVID economy.”

Tesler, a former chief operating officer for MassDOT, stepped into a greater leadership role amid the controversy at the RMV. He was appointed as acting registrar in June 2019 following the resignation of former Registrar Erin Deveney. A year later, Pollack appointed Tesler as the full-time, permanent registrar.

Aloisi, who spent most of 2009 as transportation secretary, praised Tesler’s interim elevation as “a solid choice & good news” for the state.

“I’ve known Jamey for a long time; he was at my side when I needed strong, thoughtful counsel,” Aloisi tweeted Thursday morning. “He’s first rate #mapoli and I’m relieved & hopeful by his selection.”

Asked Thursday how he intended to handle filling the permanent secretary role, Baker said he is still drafting a plan and praised Tesler for stepping up in the meantime.

“He’ll make it possible for us to create a plan and pursue a strategy for replacing the secretary that will be able to be thoughtful and will give us some time to think about what we want to do there,” Baker said.

Before joining the Registry, Tesler worked in 2019 as chief of staff at Suffolk Construction and before that he worked beteen 2015 and 2019 as assistant secretary for procurement, interim chief of staff and chief operating officer at the state Department of Transportation. Before his work in the transportation department, Tesler spent more than 18 months at Greenberg Traurig, almost three years as general counsel in the state treasurer’s office, and in legal roles at the MBTA (2005-2009) and governor’s office between 2001 and 2004.

The advocacy group Transportation for Massachusetts congratulated Pollack and expressed appreciation for her service, while pointing out that it disagreed with many of her decisions. T4MA Director Chris Dempsey called Tesler a “smart and capable public official” who “will be able to step into the Acting Secretary role on Day One.”

“Governor Baker should seek a permanent Secretary with the vision and expertise to bring real change to the state’s approach to mobility,” Dempsey said. “Massachusetts is poised to deliver on its potential of an efficient, safe, high-performing transportation system that works for everyone in the Commonwealth — but it needs leadership to get there.”

Pollack is slotted for deputy administrator, effectively the number two role at FHA, though she will also serve as its acting administrator until the U.S. Senate confirms someone to the permanent job.

Pollack’s departure to Washington adds to the list of New England political figures who have joined the Biden administration, including Rhode Island Gov. Gina Raimondo, tapped as commerce secretary, and Boston Mayor Martin Walsh, tapped as labor secretary.

Baker said the rapid change in key players “complicates things” for his team.

“If you told me at the start of all this that I was going to lose two members of our Medical Advisory Board, the mayor of the city of Boston, the governor of Rhode Island and our secretary of transportation in the space of about 20 days, I would’ve taken that bet,” Baker said.

Another member of Baker’s cabinet, Public Safety and Security Secretary Thomas Turco, had announced plans to retire at the end of 2020 before opting to remain on the job into 2021 to assist with COVID-19 response and implementation of a new major police reform law.