The Treasury Department was making difficult political and financial calculations Friday as officials finalized contingency plans to manage the nation’s finances and keep the government operating if its debt ceiling is not raised.

Department officials were also determining when to detail those plans to the public and calculating just how much money will be available to fund government obligations if lawmakers miss Tuesday’s deadline to raise the ceiling.

The Treasury has already decided to save enough cash to cover $29 billion in interest to bondholders, a bill that comes due Aug. 15, according to people familiar with the matter.

Projections computed by outside analysts show that the Treasury is likely to have enough cash to make most payments on Wednesday, including Social Security.

But officials were not yet certain which payments they could make because they didn’t know how much money they’ll have, according to people familiar with the matter. Government funding levels — a mixture of spending, borrowing and tax revenue — are becoming increasingly volatile as the deadline over the debt ceiling approaches, making it harder for officials to predict cash levels.

No matter what, within days of missing Tuesday’s deadline, the government would lose its ability to make all payments.

It’s unknown whether the government would pay most bills as they come due — while saving money for interest payments — or choose which obligations to meet and which to leave on the table unpaid. That process, officials said, would be extremely difficult.

In the meantime, federal agencies and their employees — like the rest of the nation — have been left waiting for answers.

Much as in the anxious days in April before a last-minute deal in Congress averted a government shutdown, agencies have received little guidance about how to prepare for a possible default.

It did seem increasingly likely, however, that in a default, civil servants would have to come to work, even if the government can’t pay them.

“There has been absolute silence,” said Carol A. Bonosaro, president of the Senior Executives Association, which represents about 7,300 top career executives in the government.

“We have two working days to go,” Bonosaro said. “No one has received any instruction. It’s like pushing a marshmallow.”

At 4:44 p.m. Friday, Health and Human Services employees received an e-mail from Secretary Kathleen Sebelius saying that they were expected to report to work next week.

Treasury officials believe there is still enough time for lawmakers to strike a deal and were leary about announcing any contingency plans, fearing that lawmakers might wrongly believe they had more time, according to people familiar with the matter.

Congress is scheduled to be in session all weekend.

The administration could detail emergency plans this weekend, however, if there is no progress.

Treasury did win some relief Friday.

Moody’s, a credit-rating firm, signaled that the United States was likely to retain its AAA credit rating if the Treasury doesn’t miss a bond payment.

That leaves Standard and Poor’s as the only credit-rating firm seriously threatening the United States with a downgrade. It usually takes two firms to downgrade before securities are affected.

Friday delivered a second positive indication for Treasury during a meeting between top bank executives and officials at Treasury and the Federal Reserve Bank of New York.

At the meeting, bank representatives made clear that they intended to continue to buy U.S. bonds at regularly scheduled auctions even if the debt ceiling is not raised. That was a relief for officials worried about whether they would be able to continue to borrow as existing debt came due.

Still, if immediate pressures are relieved, failure to raise the debt limit by Aug. 2 could lead to downgrades and a long-term decrease in confidence in the United States.

“It’s a bright line that has not been crossed in previous debt-ceiling impasses,” said Jay Powell, a former senior Treasury official during President George H.W. Bush’s administration. The government “is running down its cash from that point forward with no ability to borrow,” he said.

Reaching the debt limit doesn’t necessarily mean the government will shut down, as when there are no appropriations by Congress to keep agencies running. But by not raising the debt ceiling, Congress hasn’t given the administration the money it needs to pay employees.

Several experts say that means employees must keep going to work. The government might issue their paychecks late, this theory goes, but they wouldn’t be sent home.

“The collision with the debt limit is a different game” than a shutdown, said Joseph J. Minarik, who was chief economist at the Office of Management and Budget during the Clinton administration and now is senior vice president and research director at the Committee for Economic Development, a business-led public policy institute.

“Congress has said the money it authorized must be spent,” he said. “Treasury may not have the cash to pay them, but [employees] are still expected to show up for work.”