With airport security lines growing and the summer travel season looming, Congress has agreed to shift $34 million to hire 768 additional security officers and pay overtime to help alleviate long lines at airport security checkpoints.

Homeland Security Secretary Jeh Johnson and Transportation Security Administration Administrator Peter Neffenger said at a news conference Friday that the agency has developed a plan to boost the ranks of screeners, but that the traveling public should be prepared to wait and should arrive two hours before domestic flights.

The union representing TSA officers told House and Senate leaders this week that 6,000 additional screeners are needed - and 768 will not offset the numbers lost through attrition.

TSA spokesman Michael McCarthy said some of the new screeners would likely end up at Philadelphia International Airport. "I can't say for certain, but most likely," he said, "because they will be going to the busiest airports, and Philadelphia is one of our busiest airports."

American Airlines said it plans to hire several hundred contract workers this summer at its hub airports, including in Philadelphia, to assist the TSA with non-screening functions - such as returning empty bins from the back to the front of the checkpoints, and telling passengers what they need to remove from their bags before going through the checkpoint.

"Ultimately, the goal is to free up TSA officers to open additional screening lanes," said American spokesman Ross Feinstein.

"This is not a solution," he said. "This is not going to eliminate wait times, but we are going to see what we can do to ultimately assist our customers. Anything can help here. Our customers are frustrated and we feel the same way."

At Chicago O'Hare International Airport, lines on Thursday were an hour and 45 minutes to clear security, Feinstein said.

At Dallas-Fort Worth International Airport, American held flights Friday morning because passengers were waiting in security lines.

"Between 7 a.m. and 7:30 a.m., five departures had to be held because we were missing way too many passengers," Feinstein said. "We were missing 30 passengers for a flight to Orlando. We had to depart, and we left those passengers behind."

"This is not even summer travel yet," he said.

Lines in Philadelphia "are longer than usual, but compared to other airports they do not look as bad," Feinstein said. American operates 70 percent of the flights at Philadelphia International.

TSA has about 42,500 screening officers, down from 47,147 in 2013. The number of travelers flying has risen from 643 million to 740 million in that time, the agency said.