IF anything in world affairs today could be called certain, it is that Moscow would do precisely what it did when the Republican presidential candidate for reelection, Ronald Reagan, tried to send a private and personal message to the new Soviet head of government, Konstantin Chernenko.
The Kremlin declined to receive the messages.
The mere fact that a message was sent testifies to a remarkable lack of sensitivity around the White House about how other people and other countries think and behave.
In case anyone hadn't noticed, this is an election year in the United States. The incumbent President is a candidate for reelection. His chances of winning are rated more or less even depending on what day a sample poll is taken, what rival candidates do or say, the prospective behavior of the economy between now and election day, and the weather.
Republican prospects are not improved by the large increase in black registration and in black voting that the Rev. Jesse Jackson has achieved. No one need be told that for many a reason the majority of new, and old, black voters are not going to vote for Mr. Reagan. Fairly or unfairly, they think he has not done much for them.
And there is another large segment of American voters who have veered away from Mr. Reagan over the past three years. The polls all agree in identifying a stubborn negative ''gender gap.'' It's interesting that whereas President Dwight D. Eisenhower enjoyed a favorable ''gender gap,'' Mr. Reagan has developed an unfavorable one. Women like him and trust him significantly less than do men.
There are various explanations for this phenomenon of 1984. One is that Mr. Reagan has talked too much for the taste of women about such ideas as winning nuclear wars and being tough on the Soviets. His rhetoric has made war seem more possible than before he took office.
There is one obvious way to try to turn this ''gender gap'' around. That would be a friendly meeting with the new head of the Soviet government with a lot of reassuring talk about the possibility of reducing the number of nuclear weapons each country has on line aimed at the other.
For any professional politician around the White House, a dreamboat scenario would have the Soviets inviting Mr. Reagan to the Kremlin in May or June as a follow-up to his trip to Peking next month. The sequence worked wonders for Richard Nixon in 1972. Why couldn't it work again in 1984?
The answer is that it is just too obvious. Mr. Reagan now wants a handshake from them. He wants peace doves flying round his head when he meets Mr. Chernenko. It would be to his political advantage at home to have them invite him over. But what is in it for them?
Washington has covered up the embarrassment of the turndown by speculating that there may be sharp disagreement inside the Kremlin over whether to resume arms-control talks with the United States; one group is said to be favoring while the ''hawks'' prefer to build now and talk later - borrowing Mr. Reagan's own formula from 1980.
More plausibly, the Soviets are wondering whether Mr. Reagan is going to be reelected. For them, it would be a gamble. Suppose they help him with a new ''let's be friends'' scene and then he fails to win. In that case they will find it more difficult to deal with his Democratic successors, who will not be grateful to Moscow for help for their opponent. Even if Mr. Reagan does win with an assist from Moscow, can the Soviets be sure that a person who has said such unfriendly things about them in the past would actually deliver on promises made when so obviously in need?
The Soviets made it fairly clear in 1980 that they preferred Mr. Reagan to Mr. Carter, who simply baffled them. They had done business with both Richard Nixon and Gerald Ford. Their inclination was to think that they could deal with Republicans no matter how anti-Soviet the rhetoric of Republicans in the campaign. But Mr. Reagan has not proved to be, in their eyes, a Nixon-Ford type Republican. They see him as being ideological rather than pragmatic. They can't figure him out.
Under these circumstances it is natural enough for people around the President to think it a bright idea to send Gen. Brent Scowcroft, who used to work for Gerald Ford, to Moscow with a personal letter from the President and ''additional authorized comments.'' But it was just as natural for the Soviets to ignore both letter and comments.
If Mr. Reagan wants the Soviets to help him overcome this ''gender gap,'' he will have to raise the bid.