With a mixture of enticements and veiled threats, Soviet Foreign Minister Andrei Gromyko has used a three-day visit to election-gripped West Germany to warn against the planned deployment of new US medium-range nuclear missiles here this year.
When he leaves, Mr. Gromyko can return to Moscow content at having sown a few more seeds of doubt in West German minds.
''If I were Gromyko,'' a Western diplomat said, ''I would advise the Kremlin to keep quiet and await the outcome of the German election before deciding on any new disarmament initiatives.''
Mr. Gromyko arrived in Bonn Sunday in the midst of a bitter campaign for the March 6 general election, dominated by debate over NATO plans to station cruise and Pershing II missiles in Western Europe to counter Moscow's arsenal of triple-warhead SS-20 rockets.
The timing of the visit was no coincidence. The Kremlin has made clear its preference for West Germany's opposition Social Democrats, who are fighting to oust the conservative-led government of Chancellor Helmut Kohl, which took power in a parliamentary coup last fall.
Social Democratic challenger Hans-Jochen Vogel was received for almost three hours by Soviet leader Yuri Andropov in Moscow last week and presented with what appeared to be attractive new Soviet concessions on the missile issue.
At the same time, Moscow's Communist Party daily Pravda attacked Mr. Kohl's Christian Democrats for ''in the most fervent way supporting the aggressive course of Washington.''
Gromyko was more restrained in comments on the German political scene at a Bonn news conference Tuesday. He said he had not come to campaign for any party but to support those elements of West German policy favoring detente and disarmament.
He repeated previous Soviet contentions that an approximate balance of medium-range missiles already existed in Europe and was vague when asked if Moscow was really offering to scrap SS-20 missiles or only to withdraw them beyond the reach of Western Europe.
The veiled threats came in a dinner speech Monday night in which the veteran foreign minister said deployment of the Pershings, which could hit Soviet targets within eight minutes of being launched from West Germany, would mean ''an extended nuclear confrontation for the whole world, with all its consequences.''
The Soviet Union would be forced to take countermeasures to restore the nuclear balance at a higher level of armaments, he said. The West German conservative daily Die Welt reported the speech under the headline ''Gromyko threatens with more arms, lures with trade.''
On one point, Gromyko was categorical. Reports that American and Soviet negotiators had reached an informal deal - later vetoed by both governments - at the Geneva missile talks were completely false, he said, blaming the lack of progress on the Reagan administration's inflexibility.
It is hard to tell what impact the Gromyko visit had on West Germans, deeply worried by the arms race. Private polls conducted for the Bonn Chancellery last fall suggested a clear majority favored at least delaying the deployment of US missiles and did not believe either Moscow or Washington was negotiating seriously.
The polls have been discounted by Kohl's aides, who say the questions were slanted toward such responses. But there has been no convincing evidence since then to contradict this picture of public opinion.
Mr. Vogel, whose trips to Washington and Moscow seemed to give the Social Democratic campaign a substantial boost, urged the Reagan administration to move from its opening proposal of a complete ban on all land-based missiles - the so-called ''zero option'' - and show more flexibility in the Geneva talks. He endorsed the Soviet argument that French and British missiles must be counted in any nuclear balance, and said the West should cancel its deployment plans if Moscow accepts a ''radical reduction'' in its medium-range arsenal.
And the anti-nuclear Green Party, which according to latest polls could end up holding the balance of power in Parliament after the March election, favors unilateral renunciation of the Western deployment.
The polls show the ruling Christian Democrats in the lead but falling short of an absolute majority. And Mr. Kohl's government, visibly disturbed by opposition gains in the polls, has so far stuck to the ''zero option,'' although Foreign Minister Hans-Dietrich Genscher briefly theorized aloud about a possible ''interim result'' before he was pulled back into line last week.
(The US, meanwhile, has clarified its own position, according to United Press International. The US is sticking to its position that medium-range nuclear missiles should be eliminated in both Eastern and Western Europe, but US arms negotiators are authorized to listen to any reasonable counterproposal from the Soviets.
(This policy statement came in the aftermath of the firing of Eugene Rostow, director of the Arms Control and Disarmament Agency, and reports that suggested US negotiator Paul Nitze had gone beyond his instructions in private deals with his Soviet counterpart last summer.
[White House spokesman Larry Speakes said Mr. Nitze ''has always been authorized to explore any flexibility in the Soviet position'' and was not reprimanded for trying to work out an informal arrangement with the Soviets. But he added that the agreement dispatched to Washington was ''inadequate . . . and not the basis for a solution.'']