With the summer travel season underway, fliers snarled by long airport security lines are demanding to know what's behind the delays.

A former top Transportation Security Administration (TSA) official says staffing errors at the agency is to blame.

"TSA has made bad assumptions about the level of personnel resources necessary to process the two million passengers a day that come through," Tom Blank told CNBC's On The Money in a recent interview.

Blank served in senior posts from the agency's founding under the presidential administration of George W. Bush in 2001. He created the TSA's security policy and left in late 2005 after serving as the agency's number two official, and is frequently referred to as one of the agency's "founding fathers."

Blank also pointed to the fact that TSA's estimates of how many travelers would sign up for TSA preliminary screenings, or PreCheck, were way off.

"They assumed that the TSA PreCheck program was going to create enough [efficiency] and speed enough people through that they could do without some three thousand less transportation security officers," he said. Apparently, that assumption has been found wanting.

Under TSA's PreCheck, for an $85 fee fliers share personal information and are fingerprinted. In exchange, for up to five years, travelers can move through security checkpoints faster by keeping their shoes on, not being asked to remove liquids, or having to turn on laptop computers.

While TSA projections had 25 million getting on board, fewer than 3 million people are reported to have signed up.

"They (TSA) agreed with Congress to cut the funding from 45 thousand personnel down to 42 thousand," Blank said. "That turned out to be an error in judgment, and that's one of fundamental reasons that we're seeing the situation we have."

"The fact is, this is major incompetence" aviation consultant Mike Boyd told CNBC. As for the long security lines, he tells CNBC "there's not a single reason the TSA has given for this that you can really look at. "

Addressing the observation that screeners were cut, Boyd added that "they knew how many people were signing up for PreCheck."

Blank also said that "another key issue is TSA's bad report card on security performance."

Last year, TSA failed to detect explosives or spot weapons in 95 percent of the internal undercover tests conducted.

In response, Blank said, current TSA administrator Peter Neffenger pulled officers off the screening line for retraining. He added that Neffenger is "changing the culture from one of convenience to one of security.

And, Blank explained, if agents are more careful and linger over images, "that axiomatically is going to slow things down."

"What we have is a system that needs to be completely rebuilt," said Boyd, who runs his own consulting firm, Boyd Group International. He added that the near total security test failure points to the need for more extreme changes at the TSA.

"We had a 95 percent failure rate, that alone doesn't mean you change things, you throw the people out at the top. If anybody thinks this is better than what we had before 9/11, you're dreaming,"said Boyd. "This is all for show and not a lot of go."

Both men pointed to the fact that, in the TSA's 15 year history, there have been six administrators.

"Turnover at the top that does create a situation where the next run down becomes kind of the permanent leadership of the agency," Blank said.

When asked if he thought the issues at TSA will be fixed anytime soon, Boyd replied, "No way."

"Let's stop acting as if the TSA is the victim of something that came along. We are the victims of really, really bad sloppy management and that's why we're paying the price."

On the Money airs on CNBC Saturday at 5:30 am ET, or check listings for air times in local markets.