Aside from the airlines, the change has sparked mass opposition from some pilots, flight attendants, federal air marshals and insurance companies. Politicians have also voiced concerns.
Flanked by flight attendants and pilots, Rep. Ed Markey, D-Mass., held a press conference at Boston's Logan Airport today, in which he urged the TSA to abandon its new policy. If the TSA does not, Markey said he would introduce legislation to prevent knives from being allowed on planes, the Associated Press reported.
The Flight Attendants Union Coalition, which represents nearly 90,000 flight attendants, launched a wide campaign to kill the TSA policy change two days after it was announced. Flight attendants posted a petition on the White House's "We the People" website, asking the Obama administration to "tell the TSA to keep knives out of the cabin." The petition now has more than 26,200 signatures.
"Our nation's aviation system is the safest in the world thanks to multilayered security measures that include prohibition on many items that could pose a threat to the integrity of the aircraft cabin," the coalition, which is made up of five unions, said in a statement last week. "The continued ban on dangerous objects is an integral layer in aviation security and must remain in place."
Mike Karn, the president of the Coalition of Airline Pilots Association, which represents over 22,000 professional airline pilots at carriers including American Airlines and US Airways, also said in a statement that the organization will "categorically reject a proposal to allow knives of any kind in the cabin."
However, the Air Line Pilots Association, the largest airline pilots union in the world, representing nearly 51,000 pilots, supports the TSA's new carry-on policy change.
"ALPA supports TSA efforts to streamline security and shift focus to individuals who intend to do harm. This will standardize TSA policy with the international community," the organization said in a statement. "Common sense risk-based security screening initiatives, like Known Crewmember and Pre-check, are the answer to protecting our nation's air transportation system. These TSA initiatives increase resources for screening so that they focus on the real security threats instead of objects."
ABC News' Genevieve Brown contributed to this report