THIS is the time to move toward stabilizing the relationship with the Soviet Union. Stabilization and especially an improvement will not come easily. The issues dividing the two superpowers are too great and mutual suspicions are too deep to expect a quick breakthrough.
Any undue optimism that existed has surely diminished after a meeting between Soviet Minister of Foreign Affairs Andrei A. Gromyko and United States Ambassador Arthur A. Hartman. According to the Soviet news agency Tass, nothing said by the US envoy indicated that the White House has ''assumed more sober stands meeting the interests of the consolidation of peace.''
While the Kremlin despises Ronald Reagan, it also views him as a master politician. And the Soviets fear that new peaceful overtures from Washington are essentially a ploy to help the President get reelected. The Soviet leadership also claims that it will not participate in this ''deception'' aimed at world public opinion. Surely, the Soviet Union is not interested in allowing Mr. Reagan to have it both ways during the election year: to continue his hard-nosed policy and yet to appear to the voters at home and the West European public as a wise and tough-minded champion of peace and arms control.
On that score there seems to be no disagreement between the opinion of the late Yuri V. Andropov and Konstantin U. Chernenko, the new Soviet Communist Party general secretary. But public statements by the two leaders suggest that there may be some difference in the degree of open-mindedness with which Mr. Chernenko treats new American offerings.
On Sept. 28, after the Korean airliner tragedy, Mr. Andropov issued an unusual personal statement charging that US behavior had eliminated any remaining doubts about the hostile nature of the Reagan administration against the Soviet Union. No similar finality is evident in Chernenko's pronouncements. The new leader sounds guarded, but open-minded, willing to evaluate US proposals seriously as long as words from Washington are coupled with deeds. The difference between the two approaches is subtle but not unimportant.
The only way to find out whether Mr. Chernenko means business is to take him at his word and to test his flexibility with new US initiatives. In the March 2 speech in Moscow, the general secretary specifically listed areas where progress has to be made in order to achieve a ''true turning point'' in US-Soviet relations.
Some of Chernenko's suggestions - like a nuclear freeze - are unacceptable to the Reagan administration. But others are worth looking into. On the top of the Soviet leader's list is ''liquidation of obstacles'' - namely, the deployment of Pershing II and cruise missiles, an alleged stumbling block, impending negotiations on both intermediate-range and strategic nuclear weapons.
Unlike Andropov, Chernenko has not demanded a dismantlement of the US missiles as a condition for going back to the bargaining table. His formula - liquidation of obstacles - is ambiguous and is open to differing interpretations.
Why not pick the most optimistic: that the Kremlin is interested in some way out of the corner it put itself into when it walked out of the Geneva talks. It may be in US interests to offer Chernenko a helping hand.
The way to do this is to merge two sets of negotiations - strategic and intermediate-range systems. The Soviets could save face by not having to return formally to the intermediate arms talks.
''Merging the two sets of discussions is a remarkably bad idea,'' a White House aide said. He and other administration officials warn that the merger would inevitably give the West Europeans a role in influencing US positions. Many governments in Western Europe desire the US nuclear umbrella, but for political reasons are reluctant to endorse anything nuclear in public.
Similarly, the US administration is understandably reluctant to award the USSR for the disruption of the Geneva talks. The Soviet gamble has failed. The walkout did not produce a crisis in NATO, and in most West European countries peace movements are on the decline.
Does Mr. Reagan want nuclear arms control or not? If yes, merging the two negotiations is inevitable. Moscow will not come back to the talks on intermediate-range systems. Nor will the Kremlin sign an agreement on strategic weapons which would ignore Pershing II and cruise missiles capable of destroying targets inside Soviet territory. Another advantage of merging the negotiations is the opportunity to develop new trade-offs. With more weapons being discussed, ways could be found to go around the contentious issue of compensating the USSR for French and British nuclear arms.
Mr. Chernenko's suggestions also included a resumption of talks on the comprehensive nuclear test ban. These discussions were interrupted allegedly because of verification difficulties. But the Soviets are increasingly accepting the principle of on-site inspection. And unless Mr. Reagan has some other hidden reasons, nothing can be lost by giving the talks another try.
Finally, Chernenko called for the speedy determination of an agreement banning chemical weapons. Charges of Soviet use of ''yellow rain'' and of Iraqi use of mustard gas against Iran make this a particularly urgent task. And a recent Soviet announcement accepting (for the first time in years) some form of on-site inspection puts the task within reach.
None of these steps would require substantive concessions to the Soviet Union. But the possibility cannot be discounted, despite good-faith efforts by the US, that the Kremlin will refuse to break the current deadlock.
But then the US would lose nothing by demonstrating to the world where the responsibility for the diplomatic stalemate lies. Conversely, it is a certainty that without new substantive - not just rhetorical - US moves, the tiny window of opportunity in US-Soviet relations will close again. Nobody would benefit from that.