Despite their failure to foresee the current recession and triple-digit budget deficits, Ronald Reagan and the Republican Party could "luck out" during the congressional elections this fall if the worst is over and unemployment--though high--is on the way down.

According to both critics and defenders of Reaganomics, that's a highly probable scenario. Two of the president's chief political aides, Ed Meese and Jim Baker, told reporters the other day that the economy will work its way out of recession in the late spring or early summer of this year, and the recovery will be a "substantial one."

Democratic economists Walter W. Heller and Charles E. Schultze have been warning Democratic politicians for some time that all of the failures of Reaganomics in 1981 will do the Democrats little good at the polls in 1982 if the trend in the economic statistics is going Reagan's way. And they think it will be.

A few pessimists think the recession will run deeper and longer. Henry Kaufman, for one, sees interest rates starting a new upward climb by mid-year. And to be sure, the recovery seen by Heller and Schultze provides only a brief respite. Along with conventional Republican conservatives like Herbert Stein and William J. Fellner, they believe that unless Reagan does something to reduce prospective deficits of $150 billion to $200 billion a year for fiscal 1983 and 1984, the nation will lapse into yet another recession with double-digit interest rates and inflation.

But politicians mostly care about what happens today and tomorrow, not next year and the year after. They know that if the unemployment rate gets up to 9 to 9.5 percent in the next few months (highest since the Great Depression), then moves down to 8 to 8.5 percent by election time, the perception of the electorate will be that the worst is over.

Says a former high official of the Carter administration: "A declining jobless rate--even if the level is too high--will ease the fears of the vast majority of those employed over their own job security. And those guys getting paychecks will probably be benefiting from lower inflation rates, and lower interest rates."

But how about those huge deficits the Reagan administration now concedes will be overhanging the financial markets for the next three to five years? Says a frustrated Democratic economist: "The average Joe doesn't give a damn about budget deficits. That's for Wall Street and the big money guys to worry about."

The consensus is that for most of this year, the White House will be bragging about a reduced inflation rate --the result of the recession, favorable food and energy supplies, lower interest rates and slowed wage demands as major unions seek to protect jobs, instead of pricing their members out of the market.

So if the Baker-Meese scenario is right, the Republicans will be advertising their success in "getting the country moving again" at the precise moment that the nation is losing a competitive edge in many markets abroad and at home, with 8 million people still unemployed, poor families suffering a loss of welfare services and a $150 billion budget deficit on the horizon. And there's no reason to think that a majority of the electorate won't buy it.

But that won't change the longer- term reality: outside of the Reagan administration, most economists agree that even if there is an upward blip this fall, the underlying economy is likely to be in trouble so long as those deficits are overwhelming. The Federal Reserve can be expected to continue the kind of money policy that produces high interest rates, re-creating the same old pattern of crunching housing and auto sales and pushing unemployment up again, this time from an extremely high "low" point.

That's why most observers outside the Reagan administration believe that the President has made a deadly mistake in ruling out a tax increase for fiscal 1983 and 1984. Presumably, Reagan regards a tax increase as an admission of failure. He came in with a radical program of tax cuts, accompanied by boosts in defense spending, all in an environment of "faith" in Reaganomics that would balance the budget.

Through the November elections, Reagan may be able to get away with it. But what of the presidential year 1984? As one of Reagan's neo-conservative gurus, Irving Kristol, wrote early in the game: "If it (supply-side economics) fails --well, then conservatives can concentrate on nostalgic poetry and forget all about political economy. Someone else will be in charge of that."