While President Reagan's attention is focused on missiles, arms controls and collapsing Mideast peace plans, some members of his administration are mapping a strategy they hope will improve his standing with women.

Since launching his 1980 presidential candidacy, Reagan has consistently received a lower rating from women voters than from men. This "gender gap" has grown during his presidency, to the distress of his political advisers.

Now, Margaret M. Heckler, the new secretary of the Department of Health and Human Services, is trying to do something about it. Backed by other women in the administration, the former Massachusetts congresswoman is trying to get the president to speak out on behalf of women's pension rights and in support of legislation providing tax credits for day care.

The idea has not exactly caught fire with the male higher echelon at the White House, which usually keeps "women's issues" so far on the back burner that they're not even warm.

When day care was being discussed at a White House meeting chaired by counselor Edwin Meese III, a lower-ranking official urged caution in supporting day-care credits. He argued that many women work because they want to work, not because they must for economic reasons.

The remark angered the women in the room, as it is likely to upset other women if it ever becomes embodied in administration policy.

Heckler, undaunted, argued that the government shouldn't be in the business of investigating women to see why they are using day care, and the meeting broke up without a recommendation. There will be more such meetings to come.

Like Secretary of Transportation Elizabeth Hanford Dole and other women in the administration, Heckler continues to believe that the president is committed to women. Heckler believes that Reagan will demonstrate this by speaking out forcefully on economic issues of particular importance to women.

She may be correct, but the track record would indicate that she shouldn't hold her breath waiting for the announcement.

Black support for the Reagan administration may be at an all-time low after the Chicago mayoral election, but you couldn't prove it by Meese.

Meeting with reporters at a breakfast last week, the ever-optimistic counselor was asked by host Godfrey Sperling Jr. of The Christian Science Monitor whether there wasn't evidence that the president "isn't reaching out to blacks the way many people feel he should and the way he'd like to himself?"

"No, I don't think there's any evidence that he's not reaching out," Meese replied. "Our record in appointment of blacks to the administration, I think the efforts he's made with communications and has continued to make show this . . . . I think the idea that there's some antipathy, real or otherwise, between this administration and any particular group is false."

Sperling tried again, asking Meese how he accounted for Reagan's lack of black support.

"I think there are perceptions that are incorrect in the black community fostered, in part, by some of the leaders of black organizations for their own purposes . . . ," Meese replied, adding that sometimes these leaders have met with Reagan in the Oval Office and criticized him a few hours later.

Even though the White House acknowledges that it's likely to lose the fight to keep the withholding tax on interest and dividends, Reagan has told his advisers that he doesn't intend to back down even if it means having a veto overridden.

It's preferable to lose, he has been described as saying, than look like Jimmy Carter did caving in on the $50 tax-rebate plan.

Look for former California representative John H. Rousselot (R), a reapportionment casualty in the 1982 election, to take over as White House liaison with the business community. That's one of several moves being made to bolster the public liaison division since the arrival of Faith Ryan Whittlesey.

For the first time, White House reporters have shown they can take advantage of the restrictive "mini-news conference" format used by the Reagan White House. The minis are limited to about 10 minutes of questioning, and reporters must exhaust one subject before proceeding to another.

Reagan used a similar system in California, following the tradition there, but reporters had 30 minutes to question him.

Last week, the White House press corps finally recognized that the best way to use the mini, if that's the only forum available, is to explore one subject in detail rather than use a scattershot approach and come up with snippets on a half-dozen issues.

The president wound up on the record, in some detail, on what he says the administration is doing in Central America.

A full-dress evening news conference is planned for Thursday.

Reaganism of the Week: (At a photo session with members of the President's Commission on Strategic Forces): "Some of my best friends are MX missiles."