WASHINGTON — A Transportation Department official on Tuesday defended the administration’s plan to significantly cut funding for the Essential Air Service program, but county and regional airline officials testified the drop would severely jeopardize needed rural air service.

The administration has proposed reducing funds from $109 million to $50 million for the EAS program, which gives subsidies to air carriers to provide service in certain communities. But the Senate Commerce, Science and Transportation Committee, which held a hearing on the subject, has recommended boosting it to $133 million.

Montana has eight cities with EAS service: Glasgow, Glendive, Havre, Lewistown, Miles City, Sidney, West Yellowstone and Wolf Point. The Montana delegation has fought for full EAS funding.

EAS communities in Wyoming this year are Laramie and Worland; and Rock Springs, Riverton and Sheridan have also received subsidies in the past.

The program should be limited to cities already participating and not allowed to expand, said Andrew Steinberg, assistant secretary for aviation and international affairs at the Department of Transportation.

Steinberg said the program was designed as a safety net after deregulation, not intended to be permanent. But in recent years it has grown. Before the Sept. 11, 2001, terror attacks, the department paid subsidies for 107 communities. Now it is subsidizing service for 145 communities, he said.

Steinberg also proposed to rank cities in terms of how isolated they are from larger airports. The funding then would be distributed from ‘‘most needy to least needy’’ cities, he said.

The $50 million level would effectively force out a third or more of the communities that now use the EAS program, said Faye Malarkey, vice president of legislative affairs for the Regional Airline Association. The group represents 41 U.S. regional airlines.

Malarkey also said ranking communities and giving reduced subsidies to those further down the list would lead to funding running out before the obligation to all EAS communities had been met.

Karen Miller, testifying on behalf of the National Association of Counties, said EAS is extremely important to rural communities. Noting the increased cost of fuel, operations and equipment, she advocated more funding for the program and applauded the committee for proposing an increase.

Miller also said the program needs a guaranteed source of funding, such as the Airport and Airway Trust Fund, instead of coming in part from the general fund. She said the local participation program, which requires a 10 percent match from some communities, should be repealed because many are not able to afford it.

The administration has proposed doing away with the match.

‘‘We too have abandoned the cost sharing proposals put forward in prior reauthorization packages,’’ Steinberg said.

Miller also said the $200 cap per passenger on subsidies, which was set 18 years ago, should be raised. Noting the variable cost of fuel, Sen. Olympia Snowe, R-Maine, suggested the passenger subsidy cap should be indexed to inflation.

But Steinberg noted the government has not subsidized fuel costs for larger airlines, and said he would be cautious about subsidizing one part of the industry but not others.

Miller also urged Congress to create incentives for improved service or penalties for carriers that provide unreliable service. She also recommended better marketing of EAS service to communities and a study of ways to encourage more airlines to bid on providing EAS service.

Malarkey said that despite recent increases in fuel costs, EAS carriers lack the ability to readjust subsidy rates, which are set for two-year periods. She said the DOT should allow such rate changes.

Malarkey also called for an audit of unspent funds that remain on EAS balance sheets. She encouraged allowing contracts to be signed for four or five years, rather than the current two. She said carriers trying to secure financing for aircraft find it difficult to do under two-year contracts.

Steinberg said there would be some trade-offs with longer-term contracts. Some carriers want shorter contracts, he said. Although longer contracts might result in more bidders on the front end, he said, if communities are not happy with the service, it makes it harder for the department to bring more competition there.

Steinberg said in order to improve the level and quality of service, the underlying problem of ‘‘insufficient demand to support scheduled service purely on market terms’’ must be addressed. Two things may help, he said. The first is the production of Very Light Jets, which will save fuel costs. The other is information technology that will allow carriers to ‘‘aggregate demand’’ over the Internet for nonscheduled service.

The hearing also addressed the Small Community Air Service Development Program. Established by Congress in 2000, it provides federal grants to help small communities address their air service and airfare issues.

The administration has proposed ending funding for the program, which received $10 million this year. Steinberg said the inspector general will be issuing a report on projects completed under the program, but noted that the some of the grants resulted in achievements not sustained after the funding was gone.

Miller advocated for the program, saying communities rely on it.