WASHINGTON – While Congress views the convergence of more than $600 billion in tax increases and spending cuts set for Jan. 1 as a “fiscal cliff,” the metaphor misses the economic reality of what could follow.

The image popularized by Federal Reserve Chairman Ben Bernanke could give way to a series of compounding events if congressional leaders and the president fail to compromise.

“Cliff conjures up Wile E. Coyote, and January comes, and all of a sudden you plunge into a deep recession inevitably and it all happens fast,” said Chad Stone, chief economist at the Center on Budget and Policy Priorities in Washington. “That’s not the way things would unfurl.” He said he prefers the term “fiscal slope” to describe how the effects would accumulate gradually during 2013.

Congress created the conjoined deadlines on tax and spending policy as a way to prod itself to resolve long-running disputes on fiscal issues. The cliff metaphor has reinforced the need for action, shaping the debate for more than nine months and increasing pressure for Congress to avert at least some of the tax-and-spending changes.

While negotiations have stalled over President Obama’s demand for higher tax rates for top earners and congressional Republicans’ insistence on structural changes to entitlement spending, a Republican aide says those talks will narrow to conversations between Obama and House Speaker John Boehner, R-Ohio. Failure to reach an agreement by year’s end could mean, in keeping with the metaphor, going over the cliff.

The Congressional Budget Office estimates that the U.S. would probably enter a recession in the first half of 2013 if Congress doesn’t act to avoid the tax increases and spending cuts. The unemployment rate would climb to 9.1 percent in the fourth quarter of 2013 from 7.9 percent in October 2012, CBO projects.

Neil Dutta, head of U.S. economics at Renaissance Macro Research, said critics of the cliff image understate the potential for business investment to decline and for financial markets to react negatively to legislative gridlock.

“The folks who argue that it’s a fiscal slope are really ignoring the psychological impact that it would have on the business community,” Dutta said. “We face a cliff in the sense that this would be a notorious political failure if Congress failed to avert a recession because that’s effectively what the government is threatening right now.”

“People who describe it as a slope have a point, which is that the world doesn’t necessarily end on Jan. 1, if people assume the issue will be fixed very soon,” said Alec Phillips, a political analyst and economist for Goldman Sachs Group Inc. in Washington. “At the same time, it seems pretty clear that if they don’t address the fiscal restraint that’s built into current law within a reasonable period of time, a cliff and a slope are essentially the same thing. The only difference is just the angle.”

Financial markets are operating under the assumption that Congress will reach a deal by the end of the year or early January, Phillips said. There is “not a lot of indication right now that the market is expecting an adverse outcome,” he said.

When lawmakers have expressed optimism about a deal, stocks have risen. Prices have dropped when they say negotiations are stalled, giving hints at the potential for market declines if talks fail.

The Standard & Poor’s 500 Index declined 0.5 percent in three minutes on Nov. 29, erasing an earlier rally, after Boehner said “no substantive progress” had been made toward a deal. Bond markets have gained on pessimistic news. The benchmark 10-year Treasury note yield fell for the fifth of six weeks ending Nov. 30 as Obama warned that day of “prolonged negotiations” ahead on deficit reduction.

To bolster his point that the cliff is more of a slope, Stone points to the components of the scheduled fiscal contraction and how they take effect over time. Those effects can be reversed if a deal is reached early in 2013, he said. There are several other fiscal deadlines in 2013 that could push Congress to act, including the need to raise the $16.4 trillion debt limit.

If Congress doesn’t act, the policy changes include higher income tax rates at all income levels, the end of a 2 percentage-point cut in the payroll tax, higher tax rates on capital gains, estates and dividends, and automatic spending cuts, about half in defense programs.

Most of the effects would occur over the course of the year. Because most taxes are collected through paycheck withholding, only a fraction of the effect occurs each week or month.

The spending cuts operate in a similar way because agencies spend money over time, not in lump sums at the beginning of the year.

The Economic Policy Institute, a Washington group that favors policies that benefit workers, prefers the term “fiscal obstacle course” to convey the staggered effects.

Bernanke was the first prominent official to describe the policy changes scheduled for 2013 as a “fiscal cliff,” during a Feb. 29 hearing of the House Financial Services Committee. He used the term “fiscal cliff” in his most recent public remarks on Nov. 20.