Sen. Susan Collins of Maine is vacating her senior position on the Senate Homeland Security and Governmental Affairs Committee and will shift to the Senate Intelligence Committee, filling a Republican seat formerly held by Sen. Olympia Snowe, who retired.

Collins had been the top Republican of the Homeland Security Committee but was precluded from serving another term as “ranking member” due to Republican term limits on leadership positions. Instead, she will serve on the committee that oversees the nation’s intelligence-gathering operations, the Senate Republican caucus announced on Thursday, the first day of the new Congress.

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

Collins is also maintaining her seat and will rise in seniority on the powerful Senate Appropriations Committee, which helps decide how and where federal dollars are spent. She expects to remain on the defense appropriations subcommittee, working with King to ensure funding for Maine’s defense interests, including the Portsmouth Naval Shipyard in Kittery and Navy shipbuilder Bath Iron Works.

“Our state makes enormous contributions to our national security, and Maine’s interests will be well-served with Senator Angus King being named to the Senate Armed Services Committee and my leadership on the Senate defense appropriations subcommittee,” she said.

She will also serve as ranking member of the Senate Special Committee on Aging.

King, who plans to caucus with Senate Democrats, earlier learned that he’ll serve on the Senate Armed Services, Intelligence, Budget and Rules committees, solid assignments for a freshman lawmaker.

– The Associated Press contributed to this report.