Republican politicians are expressing growing concern about their party's "gender gap"--the preference women are showing for Democrats--but some activist women are keeping watch on the Democrats as well. About 150 leading liberal women in politics, business and show business sent a lengthy questionnaire to the Democratic presidential candidates, noting that "as a majority of the electorate, we women have it in our power to choose the next president of the United States . . . ."

In general, the four who have already responded--Sens. Alan Cranston of California, Gary Hart of Colorado and Fritz Hollings of South Carolina and former vice president Walter F. Mondale--said they favor cuts in defense spending and support the Equal Rights Amendment and social programs such as the right to abortions, pay equity, job training and equal insurance benefits for women.

Women demonstrated their power in last year's elections. The newsletter of the Free Congress Research and Education Foundation, a conservative organization, cites television exit polls last November showing that women voters contributed mightily to the Democrats' showing in Senate and gubernatorial races.

Women, the polls indicated, voted Democratic heavily enough to offset the Republicans' edge with male voters and elect Govs. Mario M. Cuomo in New York, James Blanchard in Michigan and Mark White in Texas.

A poll by Penn and Schoen in April showed President Reagan leading Mondale, Glenn and Hart among men, but Mondale's 14-point edge with women gave him an overall lead of 46 percent to 42 percent over Reagan, and Glenn's whopping 25-point lead with women gave him a 13-point lead over the president. Reagan led Hart by 16 points among men, but Hart's advantage with women cut this to 3 points overall.

Most analyses show the war-and-peace issue is a major factor, and some indicate that the gap is worst with unmarried women, who prefer the Democrats by about 2 to 1. Kathleen Frankovic, director of surveys for CBS, writes that "for the first time in recent political history, the one area where sex differences have traditionally been observed war and peace is the area that is playing a major role in women's evaluation of the president."