Prsident Carter appears to be heading into the 1980 presidential campaign with the prospect that he will become embroiled in a "no-win" economic situation that could leave him vulnerable in the primaries and general election.

Although economic forecasts always are tenous, the growing consensus among both economists and worried Democratic politicians is that the economy will be in a recession next year, with inflation still rampant.

Moreover, there seems to be little, at least for the short run, that Carter can do to alter this. Even if he moved to shift policy now, it probably would not affect the economy until after the 1980 election.

Indeed, insiders concede the White House still hasn't even decided on a strategy to deal with the dilemma politically. There's no grand campaign theme or new proposal waiting in the wings.

Last week, seeking to shore up his battered economic policies, the president conferred sweeping new powers on a small group of advisers headed by Treasury Secretary W. Michael Blumenthal. Cater will attend the group's meetings personally.

Aides said the president took his steps because of widerspread public perceptions that his policies were unfocused and often contradictory - a charge that a good many administration insiders concede has some foundation.

The forecasters have been wrong before, of course. Economists widely predicted a recession for mid- or late 1978, and none occurred. At the same time, the double-digit inflation rate this year took most of them by surprise.

But the signals now are so strong that even many conservaties are fearful that the economy already may have begun sliding into a recession - possibly somewhat deeper than they were forecasting last January.

There also are these factors:

Inflation already has intensified to an underlying rate of 8 to 9 percent - from 6 percent a year ago - and few economists believe it will slow substantially without a really serious recession.

Carter's wage-price gudelines program already flagging in the face of the staggering rise in prices earlier this year, has been dealt a major setback by the courts and currently is in shambles.

Finally, even Carter's own economic advisers are conceding that Americans will suffer a decline in the "real" incomes - a situation that is difficult for any incumbent to overcome, even in less-volatile times.

Analysts say the most that Carter can hope for is that the worst of the recession will be over before the November election. (The inflation side of the equation seems almost hopeless, at least for the moment.)

The biggest danger may be that the slump will hit most fiercely near the start of the spring primaries, when Carter may be most vulnerable - particularly if Sen. Edward M. Kennedy (D-Mass.) decides to enter the race.

Key Carter political aides insist they aren't that worried. They argue the important thing isn't whether the economy has slowed, but which direction it is headed. If things are back on the upswing, Carter will come out okay.

But as Carter may recall, public perception often lags behind a turn in the economy. And an unexpected "up-tick" in the jobless rate contributed substantially to his own defeat of former president Ford in 1976.

The question is, what can the president do politically?

Some White House insiders hope that a free-swinging campaign will give Carter an opportunity to explain himself more credibly than he's been able to so far in his role as president.

"Politically, our only hope is to make people recognize that the president's balanced approach to economi c issues is the right one, even though everyone can't get what he wants," one aide says. "We feel he can do that better in a campaign.'

But to many analysts, such harking back to 1976 sounds laden with pitfalls. In 1976, Carter was new and fresh-sounding, without a presidential record to defend. And there was little real prospect of Kennedy's entering the race. CAPTION: Illustration, no caption, The Washington Post