A group of leading conservative activists joined Rep. Michael Burgess (R-Texas) on Wednesday in calling on Homeland Security Secretary Janet Napolitano to resign, charging that her “failures of judgment and poor decisions— have endangered the American public.

The call for Napolitano’s resignation is the latest in a series by Republicans in the aftermath of the failed Christmas Day terror attack on a Northwest Airlines flight from Amsterdam to Detroit. Republicans have taken aim at Napolitano in particular for suggesting that “the system worked.—

In a letter to Napolitano on Wednesday, the group of conservative leaders — including Americans for Tax Reform President Grover Norquist, American Conservative Union Chairman David Keane and American Values President Gary Bauer — called her leadership of the department into question.

“We are concerned that your performance as Secretary has not been consistent with the high standards required of your job. You have made decisions that are at best highly questionable; at worst erroneous — sometimes dangerously so. And you have on several occasions said things that have been reckless, and demonstrate a lack of understanding of the perilous realities which threaten us as a nation,— Burgess and the activists said in the letter, adding that, “We face threats of enormous proportions on several fronts, most notably from terrorists who wish to — and have demonstrated that they have the ability to — commit acts of violence in order to kill Americans and disrupt our way of life. Your past performance and lack of judgment do not give us confidence that you are able to protect the American people against these threats.—