What Bradley would buy on the ticket

It was at one of those Washington social functions where public figures mixed with reporters with the understanding that information being communicated was not to be attributed directly to the sources. It is a context in which many stories find their origins in this city.

At one point this reporter found himself alone with one of Walter Mondale's top advisers, who quickly let it be known that the Democratic candidate was fully and keenly aware of problems in dealing with both women and blacks - and that a ''surprising solution'' just might be in the offing.

This solution, the Mondale associate said, was in a choice of a vice-presidential candidate who would keep both women and blacks reasonably happy. He said that the placement of Tom Bradley on the ticket would end the possibility that Jackson might still decide to lead a black protest move at the convention. And, he asked, rhetorically, how could the women make too much of a fuss if a black is chosen instead of one of them?

This Mondale aide was leaving the clear impression that the Democratic candidate was giving careful consideration to the selection of the Los Angeles mayor.

He pointed out that Bradley in his recent contest for governor had, while losing, shown an ability to attract white as well as black and Hispanic voters. He stressed that Bradley, a former law-enforcement officer, was a black who simply didn't threaten the white community.

The choice of Bradley is within the realm of possibility. He was the first to meet with Mondale in Minnesota and have a discussion about the No. 2 spot. And Bradley, like Reagan, is from California. Earlier, at this same social function that I recently attended, a former Democratic presidential aspirant indicated that he thought if Mondale chose a woman or a black, it would show that the Democrats had pretty much given up any hope of winning this year.

But it could be argued that with Mondale far behind Reagan in polls, the Minnesotan may decide that he can win only by making a bold move. The choice of Bradley would be exceedingly bold.

This Mondale associate went on to say that Mondale's choice definitely would not be a woman. He said that the leading women possibilities, Geraldine Ferraro and Dianne Feinstein, couldn't help win the South.

But how, we asked, could Bradley win over the South? He said that Bradley on the ticket would prompt black voters in the South to pour out to the polls in record numbers. And, he added, white Democrats in the South wouldn't run away from Bradley simply because they would see him as a black who had already proved he was a public official who represented all of the people in Los Angeles.

Maybe. Our guess is that Bradley on the ticket would ensure the voting trend that appears to be already in place: with the South once again going for Reagan.

The importance then of this ''story'' or ''leak'' or whatever it is? What does seem certain is that Mondale is exceedingly troubled over his so-called women and black ''issues'' - and that he knows his choice of a running mate is key to whether he lessens or intensifies these problems.