Thousands of federal employees in Maryland would be furloughed and their work put on hold next week if Congress fails to reach an agreement soon to fund the government, the Obama administration said Friday.

The Woodlawn-based Social Security Administration would furlough 18,000 employees nationwide — more than a quarter of its workforce — and reduce services at field offices. NASA Goddard Space Flight Center in Greenbelt would send about 3,040 employees home and keep another 250 "on call."

Other federal agencies that would be affected include the National Institutes of Health in Bethesda, the Food and Drug Administration in White Oak, and the Defense Department, which employs thousands of civilians at Fort Meade, Aberdeen Proving Ground and other installations.

Agencies announced shutdown plans — and service cuts ranging from park closures to delayed benefits for military families — as lawmakers on Capitol Hill raced against a deadline to pay for government operations or close federal offices.

The Senate approved a short-term funding bill Friday, but the budget fight was expected to continue into the weekend.

The new fiscal year begins Tuesday. Lawmakers have until Monday night to strike a deal.

Economists and elected officials say Maryland, with its proximity to Washington and its high concentration of federal workers, would be hit especially hard by a shutdown. Maryland is home to some 300,000 federal employees, about 10 percent of the state's civilian workforce.

"They're families that go to work every single day," Gov. Martin O'Malley said. "Through no fault of their own, they would suffer."

The governor's staff estimated the state could lose $5 million in revenue and $15 million in economic activity for each day of a shutdown.

Those numbers assume furloughed federal employees would not receive retroactive pay as they have in the past. It would take an act of Congress to approve retroactive pay.

Republicans insisted that the fight over stripping funding from President Barack Obama's 2010 health care law was worth having.

"I don't know of anyone who wants to shut down the government," said Sen. Marco Rubio, a Florida Republican. "The only thing we want to shut down is Obamacare … that's why we're so passionate about this effort."

But agencies were nevertheless preparing for the worst.

The Pentagon said it would furlough 400,000 civilian workers and temporarily stop paying death benefits to military families. The National Park Service would close all 401 of its parks and give overnight campers two days to pack up their tents.

Calls to the Internal Revenue Service would go unanswered.

Most federal agencies were muted about their contingency plans, which began trickling out Friday afternoon. Some offered more detail than others about what a shutdown would look like.

Social Security said customers still would be able to apply for benefits at field offices but, among other things, would no longer be able to receive original or replacement Social Security cards. The Food and Drug Administration would furlough 45 percent of its staff and cease routine food safety inspections.

"It's ridiculous that we're at this point where Congress cannot decide to fund the government," said Witold Skwierczynski, president of the Social Security Council of the American Federation of Government Employees. "People have paid taxes for all their lives and we can't provide them with their service."

If a shutdown were to occur, analysts say, the economic impact would depend on its length. A few days probably wouldn't do much harm, they say. If it continued into the end of next week, that would be a different story.

The federal government last closed in December 1995, and agencies remained closed for four weeks. The impact on the economy was substantial. Closing parks alone cost nearby businesses some $14 million each day, according to the nonpartisan Congressional Research Service.