By CONNIE CASSWASHINGTON (AP) â¿¿ Two days out from the end of the year, lawmakers appeared to have made little progress toward devising a compromise to keep the nation from going over the so-called fiscal cliff at the start of 2013. All eyes were on the Democratic and Republican leaders in the Senate, who vowed to keep chipping away despite the wide gulf still separating them. President Barack Obama exhorted lawmakers on Saturday to work hard for an accommodation. But earlier, optimistic words from the Senate's top Republican, Mitch McConnell, were muted by this cautionary note from the top Senate Democrat, Harry Reid: "Whatever we come up with is going to be imperfect." A look at why it's so hard for Republicans and Democrats to compromise on urgent matters of taxes and spending, and what happens if they fail to meet their deadline: ___ NEW YEAR'S HEADACHE Partly by fate, partly by design, some scary fiscal forces come together at the start of 2013 unless Congress and Obama act to stop them. They include: â¿¿ Some $536 billion in tax increases, touching nearly all Americans, because various federal tax cuts and breaks expire at year's end. â¿¿ About $110 billion in spending cuts divided equally between the military and most other federal departments. That's about 8 percent of their annual budgets, 9 percent for the Pentagon. Hitting the national economy with that double whammy of tax increases and spending cuts is what's called going over the "fiscal cliff." If allowed to unfold over 2013, it would lead to recession, a big jump in unemployment and financial market turmoil, economists predict. ___ WHAT IF THEY MISS THE DEADLINE? If New Year's Day arrives without a deal, the nation shouldn't plunge onto the shoals of recession immediately. There still might be time to engineer a soft landing.