Reagan's prime-time press conference: a pitch to the people

President Reagan took advantage of his prime-time televised press conference Wednesday to try to bolster his sagging popularity rating and to address some major controversies confronting his administration.

His opening call for a dramatic reduction in nuclear weapons was designed to counter some of the pressure from those seeking a freeze on production of nuclear weaponry. But the President was careful to specify that such reductions made sense, in his view, only if both sides began from a basis of relative equality in their nuclear arsenals.

Regarding nuclear war itself, Mr. Reagan said: ''I just have to say that I don't think there could be any winners -- everybody would be a loser if there's a nuclear war.''

The President also sought to counter criticism that he is inflexible on the budget. Reagan warmed up his relations with the Democrats in Congress by suggesting that he would be willing to alter his budget, including some cuts in defense. He made this offer conditional on the absence of reductions that would impair his defense buildup.

For some time GOP leaders have been trying to prevail upon the President to use his considerable skills as a communicator to rally the public once again to his side.

The President, knowing that use of the media must be used with restraint, has been resisting this advice -- lest his public appeal begin to wear thin.

But a continuing decline in the polls has convinced the President that he can't put off going straight to the American people for support.

That's what Mr. Reagan has been doing on his recent trips around the country.

And that's what the evening press conference was all about, the first time since Reagan has been President that he has scheduled prime TV time in an effort to reach a bigger audience.

Other subjects touched on in the press conference:

* El Salvador elections. ''We're watching this very carefully. I think it would give us great difficulties if a government now appeared on the scene that totally turned away from the reforms that have been instituted.''

* Soviet relations. ''I think . . . they're in a more desperate situation than I had assumed (a year ago) that they were economically. Their great military buildup has, and at the expense of denial of consumer products up to and including food for their people, now left them on a very narrow edge and that's why we're proposing to our allies a shutoff of credit, with regard to the Polish and the Afghanistan situation.''

* Balanced budget. The President said he embraces, as he has in the past, the ''concept'' of a constitutional amendment requiring a balanced budget.

* Palestinian autonomy. The President said he was hopeful that progress toward Palestinian autonomy talks would continue despite recent West Bank clashes.