Somewhere in the White House, there is an Office of Planning and Evaluation, which has been looking into the matter of the gender gap -- why women are less charmed by Ronald Reagan than are men. It has gone over some 20,000 polling interviews and compiled its finding into a 12-page report only to ask a variation of the old question: What do these women want?

Well, on certain issues, their consternation is well-based. I, too, am at a loss to explain why women should be more concerned than men about the prospects for nuclear war, assuming in my ignorance that the bomb will kill men and women alike. Similarly, it is hard to understand why men are not as fearful of the economic future as are women. True, men usually make more money, and true, seniority rules tend to favor them; but unemployment, as Calvin Coolidge once so keenly noted, means being out of work.

But when it comes to other aspects of the gender gap, the administration's mystification is in itself mystifying. The poor gentlemen of the White House can not figure out why, after they have opposed the ERA and abortion, squeezed day care and blamed working women for unemployment, the ladies have not given them their votes. They pore over their surveys, a modern-day version of the blind men running their hands over the elephant, and conclude that it is women, and not they, who are confused.

There is a certain tradition in the Republican Party of not being able to see the forest for the trees. For many years it was unequivocally the party of the rich, and yet it seemed stunned that everyone from the poor to the almost rich could not identify with it. (The Democrats later did this in reverse.) Traditionally, its remedy for everything from economic stagnation to outright depression has been to reward the rich and punish the poor. This is sometimes called supply-side or trickle-down economics, but whatever it's called it cannot be called equity.

In fact, the curiosity the administration has about women is strikingly similar to the one it has about blacks. Following the election, various black Republicans (virtually a contradiction in terms) were called together by HUD Secretary Samuel Pierce to examine why so few blacks voted for the GOP in the last election.

Once again, the experts examined everything but the obvious. In two short years, after all, the administration had reduced or abolished programs -- welfare, school lunches, job training, student loans, CETA -- that are of particular interest to blacks. At the same time, the Justice Department has been lethargic when it comes to civil rights enforcement, showing vigor only when deciding that schools that discriminate racially should be entitled to a tax break.

Above all, though, the president and the GOP have championed a tax and economic policy that hurts the poor and helps the rich. It has its own reasons for doing so, good ones if you happen to believe in supply-side economics, but they are not reasons that are likely to endear the party or the president to blacks or women, both of whom make up a disproportionate share of the poor.

The real mystery is not why blacks and women are rejecting President Reagan and, in the process, his clones who run the Republican Party, but how the party itself cannot see what is happening before its very nose. By its pronouncements and actions, it has repeatedly shown that its soul resides in a country club. It has, for one reason or another, given the back of its hand to both women and blacks -- and somehow expected them both to be grateful.

Taken together, though, these groups are more than half the vote and represent the political future. Increasingly they are in the avant garde when it comes to issues and increasingly they are voting Democratic. The White House sees the numbers but seemingly cannot understand the reasons for them. That, in the end, is the ultimate insult. Like other groups, women and blacks are voting in their own interests. They know precisely what they're doing. It's doubtful that the same could be said for the White House.