WASHINGTON — Senator Lisa Murkowski of Alaska, the new chairwoman of the Energy Committee, was at a reception in Hershey, Pa., last month when aides to Representative Kevin McCarthy of California, the No. 2 Republican in the House, presented her with a party favor: a black windbreaker with the words “Chairman’s Table” on the back.

There was just one problem: The windbreaker was for a man, and far too big for Ms. Murkowski. Mr. McCarthy’s aides say they simply ran out of women’s jackets in Ms. Murkowski’s size, but to her the episode reflects a new reality on Capitol Hill.

“His staff was, of course, very apologetic,” said Ms. Murkowski, who gave the windbreaker to her husband and said she took no offense. “But I did think that was somewhat telling. We are not thinking about the women.”

The November elections brought a record number of female lawmakers to Washington. With 20 in the Senate and 84 in the House, women for the first time in history hold more than 100 seats in Congress. But the Republican takeover of the Senate has also cost women powerful committee leadership posts and presented new challenges to their wielding of power.