WASHINGTON — Transportation Secretary Ray LaHood has assured lawmakers the Obama administration will prevent the closure of 149 small airport towers as well as end furloughs of air traffic controllers nationwide as a result of legislation passed by Congress, according to officials involved in negotiations on the bill.

The disclosure came as senators sought signatures on a letter to LaHood saying that their support of the legislation “was based on the understanding that the contract towers would be fully funded.”

In all, 149 towers are ticketed for possible closure beginning June 15, including the one at McCollum Field in Kennesaw, as the FAA carries out its share of the $85 billion in across-the-board budget cuts that took effect in March at numerous federal agencies.

The letter said the towers, which are staffed by employees under contract to the FAA, are a “vital public safety and economic development asset for dozens of communities — many of them rural — in every corner of the country.”

It was circulated by Sens. Jerry Moran (R-Kan.) and Richard Blumenthal (D-Conn.).

The developments coincided with congressional passage during the day of a follow-up bill that fixed a stenographic error in legislation that cleared late last week.

It was designed to give LaHood flexibility to shift up to $253 million among various accounts to “prevent reduced operations and staffing of the FAA,” but the original measure lacked the letter “s” on the word “accounts.”

President Barack Obama is expected to sign the bill quickly.

Sen. John Thune (R-S.D.), the senior Republican on the Senate Commerce Committee, said he met with LaHood on Thursday and spoke with him again the following day about the legislation. “I think his expectation is there is enough money and enough flexibility for him to” keep the towers open and end the furloughs of FAA employees, the South Dakotan said in a telephone interview.

“I would expect him to address that based on the discussions that took place.”

He added that when he and Sen. Jay Rockefeller, D-W. Va., met last week with LaHood and FAA administration Michael Huerta, “it was understood they would take care of both of those issues if we gave them the money.” Other officials said LaHood had provided similar assurances, although they spoke on condition of anonymity because they lacked authority to be quoted by name.

Justin Nisly, a spokesman for LaHood, had no immediate comment. The Transportation Department has not yet announced how it will use the flexibility provided in the legislation.

The impetus for the legislation was private pressure from the airlines whose business was disrupted by air traffic furloughs, coupled with public outrage from travelers who were forced to endure delays.

But political calculations also figured into a mini-drama that resulted in the bill’s passage late last week, as Obama and Republicans continue to blame one another for the inconveniences caused by across-the-board spending cuts.

The White House abruptly retreated under pressure last Wednesday when it indicated it would accept an easing of the FAA cuts while leaving the balance of the $85 billion in reductions unchanged. Given lengthy political struggle surrounding across-the-board cuts, the issue was sensitive enough so that when Sens. Susan Collins, R-Maine and Mark Udall, D-Colo., initially proposed legislation that explicitly said the measure would assure the towers remain open, Senate Majority Leader Harry Reid, D-Nev., objected, according to several officials briefed on the discussions.

The wording was altered to drop the explicit reference, although the flexibility to keep the towers open was retained. It was not clear whether Reid insisted on his own behalf, as a proxy for other Democrats, or on behalf of the White House. But it was not the first time the leader has become involved in a struggle over the fate of the towers.

When the Senate was debating a different measure earlier in the year, he quietly prevented Moran from gaining a vote on a stand-alone proposal to keep the towers open.

A spokesman for Reid was not immediately available to comment.

Huerta testified recently that the cost of cancelling FAA furloughs would be $220 million through Sept. 30, leaving about $33 million in freed-up funding to maintain the towers. He also said the agency is working with about 50 communities and airport operators in hopes of arranging alternative funding.