Since announcing the change last month, the TSA has come under fire. Lawmakers, unions and airline leaders have called for the agency to reverse course on its decision, which will result in knives being allowed on planes for the first time since the Sept. 11, 2001, terrorists attacks.
The agency has said that it plans allow knives shorter than 2.36 inches onto airplanes, as well as large sporting equipment like hockey sticks and wiffle ball baseball bats.
"As I made clear both before and after the change was announced, I made this decision in an effort to focus the Transportation Security Administration (TSA) more effectively against threats that could result in a catastrophic attack," Pistole wrote in his April 3 letter, arguing that he had attempted to address lawmakers concerns about the change.
"I have addressed both the background and context for my decision as well as the outreach TSA engaged in prior to and following the announcement of this decision in the attached enclosure," Pistole continued.
However, Thompson, Richmond and Swalwell argued that the agency had not done enough to address the concerns of critics.
"Engaging with stakeholders through formal standing mechanisms, such as the ASAC, would allow TSA to solicit official feedback from airlines, crewmembers and passengers advocacy groups on TSA's intent to modify the [Prohibited Items List]," the lawmakers wrote.
"Because your letter did not mention the ASAC process, we are left to draw the conclusion that you are refusing to permit this decision to be reviewed through that process."
The TSA has said that it is planning to implement the changes to its prohibited items list on planes April 25.