A group of conservative leaders, including one Republican member of the House, is calling on Homeland Security Secretary Janet Napolitano to resign. In a letter to Napolitano, the group accuses her of having made “decisions that are at best highly questionable, at worst erroneous — sometimes dangerously so” and of having displayed “a lack of understanding of the perilous realities which threaten us as a nation.”

“Your reaction to the Christmas Day failed suicide bombing of Northwest Flight 253 was just the latest of these instances,” the letter says. Noting Napolitano’s initial insistence that the “system worked” in the incident, followed by her later retraction, the leaders write, “These sorts of wild vacillations serve no one well, and leave Americans feeling unsure of the people and the government charged with protecting them.”