“There could be a bit of a silver lining,” said Rosanne Altshuler, an economist at Rutgers University who served on President George W. Bush’s 2005 tax reform panel. “It forces us to come to terms with cuts in areas that have been difficult to touch — the military and Medicare. We may not like how the cuts are going to be done, but we better start dealing with the fact that cuts are going to have to be made.”

The latest committee, created in August as part of a deal to let the federal government borrow more money, was charged with identifying at least $1.2 trillion in spending cuts over the next decade. Its failure forces the same amount of spending cuts, with half the money coming from the military budget.

The immediate economic impact depends first on investors, who must decide whether they are now any more concerned about the nation’s financial condition. Any increase in the interest rates that the government must pay would widen the deficit, as would any decrease in economic growth. But while stock market indexes fell sharply Monday, with the Dow Jones industrial average down 248.85 points, investors continue to pay for the opportunity to lend money to the United States. Two credit rating agencies, Standard & Poor’s and Moody’s, affirmed their ratings of United States debt securities on Monday and said the failure did not change their assessment of the government’s ability to pay its debts. Fitch, a third agency, said it was reviewing its ratings and hoped to make a conclusion by the end of the month. It said in August that a failure by the special committee would probably result in a negative rating.

A second, looming question is whether Congress will extend a payroll tax break for workers and continue supplemental benefits for the long-term unemployed, both scheduled to expire at the end of the year. The tax break reduces the amount that workers must pay for Social Security; the extended benefits provide support for 3.5 million Americans who have been out of a job for longer than 26 weeks. The government will spend about $168 billion on the two programs this year. Economic forecasters estimate that a decision to end the benefits would reduce the country’s economic growth next year by more than one percentage point.

The Obama administration had hoped to wrap extensions of both benefits into a broader agreement. It now faces the challenge of rescuing a smaller compromise from the ruins of the negotiations, with some Republicans in outright opposition and others demanding offsetting cuts in other federal spending.