TSA Head Apologizes to Chicago for Long Lines: 'I Don't Know What That Was'

— -- The head of the Transportation Security Administration today apologized for hours-long lines in Chicago that left hundreds of passengers stranded overnight, many sleeping on cots at O'Hare International Airport earlier this week.

“We had a significant challenge in Chicago yesterday. I don’t know what that was. We’re fixing that,” Administrator Peter Neffenger said during an event in in Houston. “I do apologize to the people who found themselves stranded in Chicago yesterday.”

According to ABC-owned station WLS, about 450 American Airlines passengers slated to fly out of O’Hare International Airport Sunday night didn’t make it to the gate in time. Some said they waited two to three hours to get through the security checkpoints.

“We’ve got a team out there right now trying to figure out what the root cause of that were. We are not seeing that kind of problem throughout the system,” Neffenger said.

American Airlines told ABC News that it is deploying contractors to assist with non-screening functions, like moving bins and managing the queue, at its big hubs. But, as one airline spokesperson notes, this is a "short-term, temporary measure" that can't solve the TSA's chronic issues.

Chicago Mayor Rahm Emanuel announced today that the agency will soon be making changes at O’Hare and Midway International Airports, including shifting 100 agents from part-time to full-time, tripling the amount of authorized overtime, and assigning 58 additional officers to the city’s airports in the next three weeks.

“The TSA wait times at Chicago’s airports have been unacceptable. There is no excuse for passengers to wait in line for hours,” Emanuel said in a statement. “The resources we have secured are an important step in providing needed relief for the traveling public, as well as ensuring the safety and security of our passengers.”

Still, in the wake of the long lines, one Illinois lawmaker is calling on Neffenger to resign if he can’t shorten wait times by Memorial Day.

“The flying public is experiencing a high security risk and economic burden from unnecessary wait times and missed flights due to insufficient staffing at TSA,” Sen. Mark Kirk, R-Ill., said in a statement. Kirk also sent Neffenger a letter asking the administrator how he planned to use the $34 million Congress shifted to the TSA in Chicago and the nation’s other busiest travel hubs.

With the hashtag #iHatetheWait picking up steam on social media, the TSA and Department of Homeland Security last week announced that they were rolling out an “aggressive” 10-point plan to curb lines -- but DHS Sec. Jeh Johnson warned passengers that “there will be wait times” at checkpoints.