Originally, implementation was set for April 25, but the plan encountered unanticipated opposition from flight attendants, then from airlines including Delta and US Airways and then from politicians.

Pistole told the Inquirer editorial board this week that: “Absent new information, I’m planning to implement it, but I want to make sure I’ve gotten all the input that is reasonable.”

Sara Nelson, international vice president of the Association of Flight Attendants, said Pistole “will have failed to do his duty to protect our nation and provide secure air travel” if he implements the policy.

“The chorus of voices against this are near unanimous, but Mr. Pistole instead sides with the knife lobby who views this as a profit opportunity,” Nelson said in an interview. “How dare he play with the lives of my colleagues at United, US Airways and every other U.S. airline along with the passengers in our care? We won’t allow it. Whether through court action or an act of Congress, flight attendants will ensure knives are never again put in the hands of terrorists, or used in an act of criminal violence against passengers or crew,” she said.