[A] longtime aide for Sen. Bernie Sanders is leaving his post at the end of the year after decades by the prominent Vermont independent’s side.

Phil Fiermonte, Sanders’ state director, confirmed that he will leave the senator’s office at the end of December.

Fiermonte has been a part of Sanders’ staff for 20 years, while Sanders served in the U.S. House and Senate.

However, Fiermonte’s relationship with Vermont’s highest profile progressive politician dates back decades, to Sanders’ 1981 bid for Burlington mayor. Fiermonte, a Derby native, son of the local doctor and a recent University of Vermont graduate, was a community organizer in Burlington.

Fiermonte said participating in Sander’s 2016 presidential campaign and watching his rise to national prominence as a torchbearer of the left was a “jaw dropping experience” as an organizer, he said.

“It’s been a remarkable thing to be part of and to watch,” Fiermonte said.

Fiermonte noted that Sanders’ messages, though not that different from earlier in his career have resonated widely.

“I travel with Bernie all the time,” Fiermonte said. “You can’t go anywhere in this country without people just being incredibly excited to see him.”

In a statement, Sanders said he considers Fiermonte to be a “close personal friend.”

“Throughout his life, from his student days at UVM to the present, Phil has been in the forefront in the fight for economic, social, racial and environmental justice. During that time, in one struggle after another, he has been one of the outstanding grassroots organizers in Vermont,” Sanders said.

Fiermonte, 62, is the latest of several longtime Sanders staffers to depart. However, he said that he is not concerned about leaving a hole behind. Many political organizers across the country want to be involved with Sanders now, Fiermonte said.

Fiermonte also spent several years as a labor organizer in Vermont, during which time he was involved unionizing nurses at Fletcher Allen Health Care and faculty at the University of Vermont. He also served on the Burlington City Council.

After retiring from Sanders’ office, Fiermonte plans to spend time with his 96-year-old father and his partner, who lives in Montreal. Though he’s stepping back from politics, he’ll continue to be involved with social activism, he said, including as a member of the board of Rights and Democracy.

Twitter: @emhew. Elizabeth Hewitt is the Sunday editor for VTDigger. She grew up in central Vermont and holds a graduate degree in magazine journalism from New York University.