ASPEN - Federal officials are planning the next big step in the effort to cut back on those killer airport security lines.

The head of the Transportation Security Administration today revealed his agency is moving ahead with a dramatic expansion of the already-successful TSA Pre-check program to allow far more airline passengers to go through expedited airport screening.

During a question-and-answer session with ABC News Chief Investigative Correspondent Brian Ross at the Aspen Security Forum, TSA Director John Pistole said the expanded system will kick off by year's end and is to be expanded to 300 airports by the end of 2014.

"This initiative will increase the number of U.S. citizens eligible to receive expedited screening," Pistole told Ross during a featured discussion at the annual Aspen Security Forum in Colorado. The program "enables us to focus on the travelers we know the least about, adding efficiency and effectiveness to the screening process."

Pre-check allows passengers to go through a pre-screening process of background checks and fingerprint analysis in return for easier, faster boarding at participating airports.

Right now, air passengers have to apply through a particular airline. The expanded program, Pistole said, will allow passengers to apply directly to the TSA.

Pistole said the pre-screening system is part of his agency's new focus on trying to figure out the more pressing threats to security and then tackling those. By pre-screening regular flyers before they get to the airport, TSA is able to focus on passengers who are not already known to federal officials.

"Everybody's still going through security but there's no reason we need to treat someone like a terrorist if we've already looked at them," Pistole said.

Passengers admitted to the pre-check are usually allowed to go through separate security lines where they don't have to take off their shoes, remove their belts or take their laptops and iPads out of their bags.

The first airports to get the expanded pre-screening program are going to be Dulles International Airport near Washington and Indianapolis International Airport.

Pistole said his agency's goal is to have half of the traveling public go through some kind of expedited security checks by the end of next year.