"Inclusion of the EAS program in this short-term funding measure is a very positive step and one that will allow time to work on a long-term solution," Cardin said Friday in a statement.
The Essential Air Service program provides subsidies to carriers that fly to small, community airports such as Hagerstown Regional Airport. Air Midwest receives $650,000 per year under the program to fly to Hagerstown.
The subsidy is approved by Congress on a five-year basis and is set to expire Sunday.
Congress had agreed to let it expire, although Cardin and Mikulski have introduced legislation that would extend it for another five years.
Greg Larsen, Hagerstown Regional Airport's business development manager, said Friday he was "very pleased" with the stopgap funding bill, but said he still was trying to determine what its practical effect would be.
Larsen said he was in contact with officials from the U.S. Department of Transportation, which runs the Essential Air Service program, to see if the measure would be approved in time to keep Air Midwest in Hagerstown.
"The (Department of Transportation) has the hammer here," Larsen said. "They have the power to ensure carriers are abiding by their contracts."
Larsen said he would continue talks with Department of Transportation officials, but had not gotten an answer by press time Friday.
Calls to Air Midwest were not returned Friday.
This is the third time Hagerstown Regional Airport has gone down to the wire with one of its carriers under Essential Air Service contracts, Larsen said.
The airport's two previous carriers both discontinued service within weeks of the subsidy's expiration.
Larsen noted that even if the funding bill is approved in time to keep Air Midwest in Hagerstown, no tickets have been sold for flights after Sunday.
"Even if we have a flight on Monday, there won't be a soul on the plane," Larsen said.
He said it will take the airport months to build business back to current levels.
Larsen said the bill was good news, however, because it shows intent on the part of the federal government to continue the subsidy program, which will help the airport's negotiations with future carriers.
"For companies we've been talking to, they need assurance that the government wants to fund this program," Larsen said. "So overall, this bill is great news."
The Associated Press contributed to this story.