Democratic leaders in the U.S. are asking the Congressional Budget Office (CBO) to take a fresh look at the costs associated with the House FAA reauthorization package. They say changes to the bill and taxes associated with the air traffic control privatization proposal would increase the deficit by billions more than original estimates.

The leaders, including the ranking Democrats of four House committees, noted the CBO estimated that the ATC proposal in the 21st Century AIRR Act, H.R.2997, would increase net deficits by more than $20 billion over the next 10 years and by more than $5 billion in subsequent 10-year periods.

But since that estimate, “significant changes” have been made to the bill, including the addition of a tax proposal associated with the measure that would separate ATC from the FAA. The proposal “slashes revenues from aviation excise taxes by more than $15 billion per year.” Other changes of the bill include $1 billion in cuts to airport grants, an additional $945 million.

“In total, these changes...likely add tens of billions of dollars to the cost of the legislation and, thus, the budget deficit,” the ranking members noted, adding they were made without legislators being given the opportunity to provide input on the changes.

They asked the CBO to provide a full cost estimate by September 5. The letter, to CBO director Keith Hall, was signed by House Transportation and Infrastructure Committee ranking Democrat Pete DeFazio (Oregon); Eddie Bernice Johnson (D-Texas), the ranking member of the Committee on Science, Space, and Technology; Richard Neal (D-Massachusetts), of the Ways and Means Committee; and Budget Committee ranking member John Yarmuth (D-Kentucky).

The request continues an effort by the Democratic leaders to gather ammunition that could stymie the ATC measure. Earlier, House Democrats appealed to the DOT Office of Inspector General to look into the potential for lobbying activities by transportation officials in support of the ATC proposal.