Elected Republicans, however, are under intense pressure from their party’s conservative base to oppose any tax increases  a line in the sand that dims any prospects for bipartisan cooperation. Yet economists, including veterans of past Republican administrations, are vocal in insisting that the debt problem is too great to be solved without increasing revenues somehow and perhaps moving to a new consumption tax system like Europe’s.

The same economists also say a significant deficit-reduction plan is not possible unless Mr. Obama breaks his campaign promise not to raise taxes for households making less than $250,000. Last week, Mr. Obama said he would not impose that condition or any other on a fiscal commission.

The situation is complicated by a debate over how quickly Washington should act even if it could. The Obama administration, Congressional Democratic leaders and many economists are pushing for additional government stimulus measures while the private sector remains weak. But anger about big deficits has stoked the populism roiling politics, and Republicans as well as some conservative Democrats want to cut spending right now as a way of addressing perceptions among voters that government has gotten too big, too intrusive and too profligate. Mr. Obama himself proposed a budget that would freeze spending on some categories of domestic spending for three years.

Many analysts say the president and Congress could send a strong signal to global markets by agreeing this year to a package of both long-term tax increases and spending reductions, especially in the popular entitlement programs, that would not take effect until 2012. That is the recommendation of two new studies, one by the National Research Council and the National Academy of Public Administration and the other a separate joint project of the Peter G. Peterson Foundation, the Pew Charitable Trusts and the Committee for a Responsible Federal Budget.

Image Senators Evan Bayh and John McCain, right, on Jan. 26 as they discussed proposed legislation to halt discretionary spending. Credit... Alex Brandon/Associated Press

As debt rises, so do interest costs; by 2014, at a projected $516 billion, they will exceed the budget for annual appropriations for domestic programs. The government will be competing with the private sector for credit, forcing interest rates higher and imperiling future prosperity.

Foreign investors now own more than half of the publicly held debt, and officials for the largest creditor, China, have fretted publicly about the fiscal course of the United States. While few expect foreigners to dump their assets, since the resulting plunge in values would hurt them as well as everyone else, the fear is that investors will demand higher interest payments and reduce or stop future debt purchases, threatening the government’s ability to finance its borrowing.