The embattled Transportation Security Administration boss told lawmakers Wednesday that lengthy wait times recently seen at Chicago’s O’Hare Airport were “preventable” and that the fault lies with the agency -- which was not prepared for the recent surge in air travel.

TSA Administrator Peter Neffenger told lawmakers that insufficient funding and lack of manpower are to blame for the long airport lines that are expected to worsen during the upcoming peak travel period.

Appearing before the House Homeland Security Committee, Neffenger conceded the agency is short-handed.

“We are at a lower staffing level than we need to be,” Neffenger said.

Neffenger said staffing levels have been cut 12 percent since he was assigned to his post last year, and that the TSA, which has 45,000 employees, was scheduled to lose 1,600 more members in 2016.

The TSA projects that 740 million passengers will pass through its screening process this year, up from 643 million just a few years ago.

Neffenger said an additional 768 TSA workers would be ready for service by the middle of June.

Neffenger was back on Capitol Hill Wednesday to answer questions about long airport security lines that have already impacted the summer travel season.

“This is unacceptable and it’s time for Congress to act,” committee Chairman Rep. Michael McCaul, R-Texas, said. “Change is not happening fast enough.”

McCaul said the TSA crisis did not just “come out of nowhere” and airports and airlines have been “sounding the alarm for months.”

He also pushed back on the theory that wait times are longer because of increased security measures. Instead, he said the wait times are because “TSA’s broken bureaucracy has gotten weaker.”

The pressure has been building on the TSA in recent weeks after historically long wait times at the nation’s busiest airports ahead of Memorial Day and the summer travel season.

On May 15, nearly 500 people were stranded at Chicago’s O’Hare International Airport, prompting Mayor Rahm Emanuel to promise he'll hire more airport screeners.

Neffenger said the TSA planned to introduce more airport dog teams trained to sniff out bombs as well as initiatives to move 20 percent of the agency’s trained screeners to full-time from part-time.

Rep. Mark Walker, R-N.C., pressed Neffenger on what prompted the ouster of the agency’s top security official, Kelly Hoggan.

Hoggan was removed from his position following a hearing about the agency’s mismanagement.

Neffenger said Hoggan was currently on paid administrative leave but said it was a “short-term decision.”

In an email to employees on Monday, Neffenger announced a series of additional leadership changes. The position that Hoggan held since 2013 will be temporarily taken by Darby LaJoye, who is currently deputy assistant administrator.

Neffenger has also announced a new management team in charge of screening operations at Chicago O'Hare International Airport.

The changes come ahead of the Memorial Day weekend and busy summer travel season as fliers complain about long, slow airport screening lines.

The Associated Press contributed to this report.