Democratic Sen. Patrick Leahy of Vermont announced Monday he would not seek reelection next year, leaving open a seat he has held since 1975.

“I’m proud to be Vermont’s longest-serving senator, and my time in the Senate has made a difference,” Leahy, 81, said at a press conference at the Vermont State House. He said he chose the location because it was where he initially announced his candidacy for the Senate.

Leahy is the longest-serving Democrat in the Senate and is chairman of the Senate Appropriations Committee. He is the most senior member of the Judiciary and Agriculture committees. His retirement means Vermont Sen. Bernie Sanders will no longer be the junior senator from the Green Mountain State.

Leahy was elected in the Democratic wave following the Watergate scandal. He is a vocal fan of Batman and has appeared in five of the franchise’s movies, including The Dark Knight.

Democratic Rep. Peter Welch, the …