The big wild card is the stock market and the nation's financial confidence: Would traders start to panic if Washington appeared unable to reach accord? Would worried consumers and businesses sharply reduce their spending? In what could be a preview, stock prices in the U.S. and Europe dropped Friday on waning hopes that Obama and key lawmakers would reach an 11th-hour compromise.
Federal Reserve Chairman Ben Bernanke has warned lawmakers that the economy is already suffering from the uncertainty and they shouldn't risk making it worse by blowing past their deadline.
WHAT IF THEY NEVER AGREE?
If negotiations between Obama and Congress collapse completely, 2013 looks like a rocky year.
Taxes would jump $2,400 on average for families with incomes of $50,000 to $75,000, according to a study by the nonpartisan Tax Policy Center. Because consumers would get less of their paychecks to spend, businesses and jobs would suffer.
At the same time, Americans would feel cuts in government services; some federal workers would be furloughed or laid off and companies would lose government business. The nation would lose up to 3.4 million jobs, the Congressional Budget Office predicts.
"The consequences of that would be felt by everybody," Bernanke says.
Much of the disagreement surrounds the George W. Bush-era income tax cuts, and whether those rates should be allowed to rise for the nation's wealthiest taxpayers. Both political parties say they want to protect the middle class from tax increases.
Several tax breaks begun in 2009 to stimulate the economy by aiding low- and middle-income families are also set to expire Jan. 1. The alternative minimum tax would expand to catch 28 million more taxpayers, with an average increase of $3,700 a year. Taxes on investments would rise, too. More deaths would be covered by the federal estate tax, and the rate climbs from 35 percent to 55 percent. Some corporate tax breaks would end.