PORTLAND (AP) — The era of U.S. Sens. Susan Collins of Maine and Joseph Lieberman of Connecticut leading the Homeland Security Committee is over with Lieberman retiring and Collins moving to the Senate Intelligence Committee, leaving the panel without the only two chairs it’s known.

Republican caucus rules prevented Collins from serving another term on Homeland Security, which she’d served on since its creation, along with Lieberman. Instead, Collins learned Thursday that she’ll be moving to the Intelligence Committee, on which departing Sen. Olympia Snowe had served.

Collins served as chairwoman of Governmental Affairs Committee when its duties were expanded to include homeland security after the terrorist attacks on Sept. 11, 2001.

She later ceded the chairmanship of the Committee on Homeland Security and Governmental Affairs to Lieberman, a close friend, after Democrats won a majority.

Together, they had a reputation for overcoming partisan differences. “Regardless of who has been chairman and who has been ranking member, ours has been a partnership,” she said.

Collins also gave up her seat on the Armed Services Committee to make way for independent Sen. Angus King of Maine. Collins previously received special waivers from the GOP caucus to remain on the panel but felt comfortable leaving because Maine will continue to be represented.