The all-important statistic

The statistic that worries Democrats the most in the wake of the overwhelming vote for Ronald reagan is the one that says 66 percent of the whites voted for the President and 90 percent of the blacks gave their support to Walter Mondale.

In Certain parts of the deep South, in fact, the white vote for Mr. Reagan rose to 90 percrnt. In that region, Democratic politicians and officeholders are deeply concerned that a genuine realignment may be taking place, one in which the Republicans are emerging as the party of the white voters and thereby, threatening to replace the Democrats as the major force in all elections.

At the time Jesse Jackson gave his emotional and inspirational ''Our time has come''speech at San Francisco, it was widely hailed by those who were there.

It did spark that convention. And the prose may have been memorable. But it frightened a lot of whites, particularly in the South. thus, the ensuing ''white fight'' that brought about a rallying of Southern whites to Reagan's side, a trend further prodded by the Rev. Jackson's efforts to register blacks

The relatively few whites to vote against Reagan were those caught up in liberal causes: support for the federal role in public education, resistance to Reagan-led encroachments on the environment, and backing of efforts to extend civil rights.

Charles Manatt, the leading voice of the Democrats, says the party must find a way to reach out to '' more people''. He says that now is the time for Democratic leaders to find a message that will have a broader appeal.

That's exactly what Walter Mondale was saying, four years ago, when he had breakfast with a group from the news media. He said he would be spending the next year or two moving around the US in an effort to find out what people had on their minds. and on the basis of such findings he would put together his own message for 1984.

Mr. Mondale's message for 1984 was made up of what Hubert Humphrey used to call the ''old-time religion,'' a passionate support for the causes of the blue-collar workers, unemployed, blacks, and the poor.

The word that came through most often in Mondale's latter-day campaign speeches was ''compassion.'' Reagan, he charged, lacked compassion. compassion is a divisive political word. The whites read itas meaning ''more help for the underprivileged, particularly the blacks.'' And blacks read it pretty much the same way.

So no matter what Mondale said about being very careful about putting more money into social programs, he didn't build up much credibility with white voters.

Do these whites who voted in such large numbers for Reagan see themselves as lacking in compassion toward the poor, particularly the blacks? Not at all. They just believe that they have already done enough and aren't about to dig deeper into their pockets to increase their outlays for what the see to be unreasonable demands from the poor. Moreover, they believe Reagan when he insists that he has provided a ''safety net'' for the needy.

It seems clear that when the Democrats reach out to broaden their appeal they face an enormous problem: How to continue to be the party of ''compassion'' and, at the same time, convince white voters.that they won't have to pay for this compassion.