President Donald Trump has long used the building of a massive wall along the Mexican border as a resounding battle cry both for his campaigns and his rallies.

“They’re going to pay for the wall and they’re going to enjoy it, okay?" he said during a rally in Tennessee last spring. "They’re gonna enjoy it."

It’s been a long-standing promise, and a new audit from the Government Accountability Office Monday found that plans for building the wall are in chaos. The GAO, the investigative arm of Congress, found that Customs and Border Protection hasn’t determined what each segment of the wall will cost. And without those prices, CBP can’t prioritize where to start building. For example, the Border Patrol reasoned that it will cost $18 billion to build 722 miles of new border barriers but that was based on a rough average cost per mile and wasn't an actual assessment.

"Without assessing costs as part of the prioritization process, CBP does not have complete information to know whether it is prioritizing locations that will use its limited resources in the most cost-effective manner," the GAO's Rebecca Gambler wrote in her 49-page audit.

CBP also hasn't documented its plans for building a secondary border barrier in the San Diego area.

In conclusion, the GAO found that "DHS plans to spend billions of dollars developing and deploying new barriers along the southwest border. However, by proceeding without key information on cost, acquisition baselines, and the contributions of previous barrier and technology deployments, DHS faces an increased risk that the Border Wall System Program will cost more than projected, take longer than planned, or not fully perform as expected."