State transportation chief Stephanie Pollack is leaving for a top Federal Highway Administration job

Stephanie Pollack, the outgoing state transportation secretary.Nancy Lane/Pool

Stephanie Pollack, the state’s longtime secretary of transportation, is taking a key role at the Federal Highway Administration, where she could help execute President Biden’s ambitious plans to upgrade the nation’s infrastructure.

Pollack, 61, is just the latest Massachusetts resident to head to Washington for a job in the Biden administration, but the first high-level state employee and member of Governor Charlie Baker’s Cabinet to do so.

She will eventually serve as a deputy administrator at the Federal Highway Administration but will begin next week as acting administrator until a permanent leader is nominated and confirmed, Pollack wrote in a resignation letter Thursday.

“We will benefit greatly from her knowledge of transportation and breadth of experience,” wrote Thomas Everett, the agency’s executive director, in an e-mail to staff.

Baker promoted Jamey L. Tesler, head of the Registry of Motor Vehicles and former chief operating officer at the Department of Transportation under Pollack, to acting secretary, overseeing the RMV, state highways, and 15 regional transit authorities, among other divisions.

Pollack’s departure comes as the pandemic has thrown Massachusetts’ public transportation systems into flux. The Massachusetts Bay Transportation Authority is forging ahead with plans to slash service, and drivers face the prospect of Greater Boston’s worst-in-the-nation gridlock returning as daily life slowly shifts back to normal.

Pollack, a graduate of the Massachusetts Institute of Technology and Harvard Law School, had been Baker’s only transportation secretary, joining his Cabinet in January 2015 from Northeastern University’s Kitty and Michael Dukakis Center for Urban and Regional Policy.

Her six years as transportation secretary is the longest tenure in decades, and the job often put Pollack front and center, first as the MBTA emerged from a brutal winter in 2015 and then in 2019, when dual crises buffeted the administration.

Pollack juggled both a high-profile derailment on the Red Line and disastrous lapses at the RMV, where officials admitted they should have terminated a West Springfield truck driver’s commercial license before he struck a group of motorcyclists, killing seven, in New Hampshire that summer.

A spokeswoman said Pollack was not available for an interview. In a statement, Pollack thanked Baker for “entrusting me with the stewardship of MassDOT and their leadership as transportation champions.”

At a news conference Thursday, Baker called Pollack’s departure a “bummer” for his administration but said having someone attuned to Massachusetts’ needs in Washington could benefit the state.

“Most of our policy was developed by the secretary and by our team, and I would expect that a lot of it would continue as is. I do think the players changing complicates things,” Baker said, though he declined to say if he would seek a permanent replacement from outside his administration.

Baker tapped Tesler to lead the Registry in June 2019 when then-registrar Erin Deveney resigned after the deadly New Hampshire crash.

The tragedy revealed decades of bureaucratic neglect at the agency, which had failed to suspend the license of the truck driver, Volodymyr Zhukovskyy, even after receiving two notices about driving violations in Connecticut. Zhukovskyy is awaiting trial in New Hampshire.

Speaking to the Globe last year, Pollack took responsibility for the crash. “Morally, do I feel responsible, and responsible for the motorcyclists who were killed in New Hampshire? Yes,” she said.

An outside audit found that officials were so consumed with improving customer service that they pushed aside or neglected out-of-state driving violations that were mailed to the agency, leaving them to molder in cardboard boxes.

In a 41-page report released this month, the Legislature’s Committee on Transportation said Pollack and Baker’s office “failed to devote proper attention to matters related to public safety.” The report also questioned Pollack’s assertion she was not aware the RMV had shifted responsibility for processing out-of-state notices from one office to another, calling it an “abuse of the credibility.”

As part of her advocacy work before joining the Baker administration, Pollack pushed for policies to promote public transit, including some, such as raising the gas tax, that Baker had opposed. It made Baker’s decision to hire her in 2015 a surprise, though she quickly became MassDOT’s unchallenged leader.

But she also disappointed some transportation advocates as the MBTA pursued fare hikes, while the administration opposed funneling money into the system through new or higher taxes.

“You cannot change things from the inside when the inside is run by people who fundamentally disagree with your line of thinking,” Jarred Johnson, director of the advocacy group TransitMatters, said on Twitter Thursday.

Nevertheless, Chris Dempsey, director of the advocacy coalition Transportation for Massachusetts, said he believes she can be effective in the Biden administration.

“She’s going to be working for a very different boss,” Dempsey said. “Both Biden and incoming secretary [Pete] Buttigieg have expressed their willingness to rethink what highways, and especially urban highways, are.”

A number of others from the Bay State are also joining the Biden administration, including:

* Boston Mayor Martin J. Walsh, who was nominated to be labor secretary.

* Former Secretary of State John Kerry, named as a presidential envoy focused on climate change.

* Eric Lander, founding director of the Broad Institute of MIT and Harvard, who was nominated to be chief science adviser.

Laura Crimaldi of the Globe staff contributed to this report.