Transportation Secretary Sean Duffy told lawmakers Wednesday that a complete overhaul of the nation’s air traffic control system would cost roughly $31.5 billion — about $10 billion more than he estimated last month.

Duffy’s new estimate matches a “wish list” topline of more than $30 billion that has been circulating on Capitol Hill and leaving lawmakers questioning how they can secure funds, sources familiar with discussions said. The reconciliation law provided an initial $12.5 billion.

[Related: Lawmakers mull a pricey air traffic control ‘wish list’]

Duffy said in June that the overhaul would cost at least $20 billion.

Both Democrats and Republicans on the House Transportation and Infrastructure Committee pressed Duffy for more specifics on the air traffic control upgrade on top of the Transportation Department’s May framework. Sources have said previously that some lawmakers are concerned that the Federal Aviation Administration lacks the capacity to handle such a project.

“We’re looking at the FAA’s current pace of replacing the facilities is a staggering … 300-year timeline. It looks like your program wishes to get to 80 years, which I still find unacceptable,” Rep. Scott Perry, R-Pa., said at the hearing. “What changes are you looking at in the procurement process, which is badly, badly broken?”

Duffy confirmed Perry’s estimate that on the “current plan,” it would take 300 years to upgrade the system with new radios, radar systems and other aging control tower equipment. He added that the FAA will use procurement authority provided by Congress to find a single company or project manager to oversee the overhaul.

He reiterated calls from a Cabinet meeting last week for lawmakers to give the department more funding to complete the project.

“This is really old stuff. We will need more to do it,” Duffy said. “No offense to anybody, but the way Congress spends money, we’re talking $31.5 billion to do the full project. And my hope is that we’ll have an additional conversation about how we can do that — and time is of the essence.”

Duffy said funding in the reconciliation law will provide the FAA with radios, voice switches and surface movement radar.

House appropriators appear ready to boost FAA funding by $2.3 billion, to $23.3 billion, in the fiscal 2026 Transportation-HUD spending bill, which included $10.4 billion to “fully fund air traffic control operations” and boost the agency’s facilities and equipment account up to $5 billion, or $1.8 billion over the current level.

The House Appropriations Committee is scheduled to mark up the bill Thursday.

Although some of that annual funding can be used for air traffic control upgrades, much of it will go toward maintaining the current system. Sources familiar with discussions said the additional funding would likely have to come in the form of another reconciliation bill or a supplemental funding measure.

“We have the American people, the Congress, the DOT, the president, the FAA — we’re all on the same page of making this a reality, because failure is not an option,” Duffy said. “The key is we’re going to deploy these assets when we still have airplanes inside, and doing that safely is the No. 1 priority.”