Sen. Jeanne Shaheen said Wednesday she won’t run for re-election in 2026, bringing to an end a political career spanning a half century.

In a video announcement, Shaheen said it had been “an incredible honor” to serve as a state lawmaker, governor and senator. She said the decision to step aside was a difficult one, but “it’s just time.”

Shaheen, a 78-year-old Democrat, was first elected to the U.S. Senate in 2008, and is now in her third term. Prior to that, she served three terms as New Hampshire governor and as a state senator, after getting her start in Granite State politics on Jimmy Carter’s 1976 presidential primary campaign. She was the first woman in American history to be elected both governor and senator.

Her style of politics – moderate on fiscal matters but more liberal on social issues – set a model for a generation of fellow New Hampshire Democrats who followed her into the governor’s office and Congress.

Read more: In Shaheen, N.H. Democrats Have Their Leader, And A Blueprint For Campaigning

Shaheen’s announcement adds to the challenge facing national Democrats in their efforts to take control of the U.S. Senate in 2026.

In her video announcement, Shaheen said her decision did not amount to a full retirement.

”I am determined to work every day, over the next two years and beyond, to continue to try and make a difference for the people of New Hampshire and this country,” she said.

With Shaheen steeping aside, the race to succeed her is wide open.

No Democrats have yet announced interest in running for the seat. On the Republican side, former Massachusetts Sen. Scott Brown, who Shaheen defeated in 2014, is considering a run. And New Hampshire Gov. Chris Sununu said recently he is open to the idea of running for Senate, after previously saying he has no interest in serving in Congress.

This is a developing story and will be updated.