Moscow and Washington leaving door open for summit?

Like the last two holdouts at a singles-only dance, Konstantin Chernenko and Ronald Reagan may finally be edging closer to meeting one another. It's not exactly what either had in mind, and there's still plenty of reluctance all around. But in recent days the word ''summit'' has been tossed about in both Moscow and Washington.

White House sources in Washington said, in advance of President Reagan's press conference (which had not started at time of writing), that he would leave the door open for a meeting with Soviet leader Chernenko.

Asked at a Moscow press conference how the Soviet government might react, chief Kremlin spokesman Leonid Zamyatin did not reject the idea of a meeting. He noted that there were serious problems that must first be solved, but he said, ''The possibility of such a meeting exists.''

All of this, of course, needs to be put in a broader context. And, it might be added, looked at with some skepticism. Zamyatin is, after all, the same Kremlin spokesman who promised a reappearance of the ailing former Soviet leader Yuri Andropov just days before Andropov's death was announced.

President Reagan has long been under pressure, both domestically and from other Western countries, to be more forthcoming to the Soviets. And already this year he has made several private and public overtures to the Soviets.

This week, Sen. Howard Baker, the outgoing Republican majority leader, went a step further, calling on Mr. Reagan to have annual meetings with his Soviet counterpart. Reagan expressed reservations, and the White House was stung at the criticism his comments generated.

Mr. Reagan also came under some pressure from Western leaders at last week's London economic summit, where he reportedly had harsh words with Canadian Prime Minister Pierre Trudeau over East-West talks.

Mr. Trudeau, who has spent the better part of his last year in office trying to mend relations between the US and the Soviets, urged Reagan to be more forthcoming toward the Soviets. Reagan responded that his overtures had met no response.

Still, it is a presidential election year, and some Republican strategists are worried that the bad state of US-Soviet relations might be damaging to Reagan's reelection bid. Reagan himself admitted recently that he hasn't been able to shake his ''trigger-happy'' image.

The Soviets, meanwhile, are smarting. They failed to stop the deployment of new American-supplied NATO missiles in Western Europe last fall. Since then, they have undergone a leadership transition, and seem to have been in disarray over the past several months.

''They've painted themselves into a corner,'' says one Western diplomat.

It is highly unlikely the Soviet leadership trusts Ronald Reagan to tell them when the paint's dry and it's safe to walk out. In interviews, Soviet officials say they have a deep-seated mistrust of Reagan and his advisers.

''We don't trust this president,'' says one official, adding that some of the advisers around Reagan are ''anti-Soviet'' in the extreme. Still, Soviet officials have added privately all along that if the US offers something ''concrete,'' the Soviets will respond in kind.

''We will not keep you waiting,'' said one member of the Communist Party Central Committee.

So what is ''concrete''? There appears to be no precise definition, yet the phrase keeps cropping up in official pronouncements.

Chernenko, in his most recent public statement (an interview with the official Party newspaper, Pravda) said, ''Is there a need for a dialogue and for talks? Both yesterday and today our answer has been the same - yes. But a dialogue which is honest, and talks that are serious. In these we stand ready to engage at any moment.''

What kinds of steps would Moscow view as ''concrete''? Some steps Washington would clearly find impossible to take. One, which the Soviets have been demanding for months, would be to remove the new Pershing II and cruise missiles from Western Europe - a step which Washington would view as political self-immolation and extremely damaging to the NATO alliance.

Another, which the White House has already ruled out, is beginning negotiations aimed at a treaty preventing the ''militarization of space'' - specifically, banning the stationing of weapons or of missile defense systems in orbit above the earth. Reagan says such a treaty would be impossible to verify - a point the Soviets dispute.

Why are the Soviets so anxious to negotiate?

For one reason, they already have an anti-satellite weapons system that, although crude and imprecise, could be used to destroy American military satellites in time of war. But the Soviets are clearly worried at the scale and technology embodied in President Reagan's proposed space-based missile defense system, dubbed the ''star wars'' defense system.

Soviet officials are anxious to avoid a competition in space in which high-technology - complex microcircuits, lasers, and particle-beam weapons - might mean the edge in a conflict. Such Soviet technology lags several years behind the US and West Europe.

The Soviets are not unmindful that this is a US election year, and that a summit meeting might benefit Reagan's re-election efforts.

On the other hand, to continue to spurn Reagan may also backfire - making him appear conciliatory, and the Soviet Union mean-spirited or, worse, reckless. That is one reason why Leonid Zamyatin said, ''The Soviet Union's policy is a flexible policy.''

He added, ''everything will depend on when and how the questions (to be considered at a summit) are prepared.'' But ''it is time to begin this preparatory work. . . . As far as we are concerned, we have the desire to agree with the United States.''