Key Republican and independent senators and former members of the Bush administration spoke up Sunday in support of Janet Napolitano, the secretary of homeland security, despite stinging criticism last week of her comments that a Nigerian’s foiled effort to blow up a Detroit-bound airliner on Christmas Day showed that “the system worked really smoothly.”

Michael Chertoff, her predecessor as homeland security secretary, when asked on NBC’s “Meet the Press” television program whether he had confidence in Ms. Napolitano, said forcefully, “I do.”

Susan Collins of Maine, the ranking Republican on the Senate homeland security committee, said she found Ms. Napolitano’s comments “bizarre and inappropriate.” Nevertheless, she said, she has confidence in Ms. Napolitano and that she is working hard to keep the nation safe.

Senator Joseph Lieberman of Connecticut, who heads the homeland security committee and has assailed the Obama’s administration failure to prevent the Nigerian suspect, Umar Farouk Abdulmutallab, from boarding the Northwest Airlines plane, said on the same program that Ms. Napolitano had done a “tremendous” job. He said her words were “subject to a misunderstanding” and that he didn’t agree with her choice of words, but he too had confidence in her work.