The National Organization for Women hopes to increase its membership to 1 million activists, a fivefold increase, before the 1984 election campaign gets going, departing NOW President Eleanor Smeal said today.

Opening the feminist organization's annual convention here with a workshop, a news conference and a speech all focused on political targets, Smeal said politicians had better take note of polls showing that women disagree with men -- and will vote differently -- on a host of issues.

This "gender gap" found women 15 to 20 percent more negative on President Reagan last summer than men, but the gap is narrowing.

"Men are going to the original position of women," becoming more negative on Reaganomics, Smeal said. Politicians used to assume women voted as their husbands did, but "it could emerge that men vote as their wives," she added.

The cavernous convention center is festooned with old photographs of suffragist women carrying a sign quoting Susan B. Anthony: "No self-respecting woman should wish or work for the success of a party that ignores her sex."

The 2,200 delegates to the three-day gathering, who will elect Smeal's successor from among five contenders Saturday, are a boisterous lot.

They are flushed with both success and failure, the paradox of phenomenal organizational growth and their bitter loss in the campaign to ratify the Equal Rights Amendment. They may be divided over the future of their internal leadership, Smeal said, but they are united in turning to political action to advance women's rights.

Recent polls find Reagan's favorable rating increasing slightly among women, but not as fast as it is decreasing among men. The polls also show that more women call themselves Democrats than men do, oppose a weapons buildup more strongly, and now vote at a higher percentage rate than men. Younger women are significantly more active, according to polls collected by NOW.

Smeal said the 16-year-old organization is raising $1 million a month, more than the Democratic National Committee, toward a 1984 campaign chest.

"We intend to defeat people who were against the ERA," she said. Many women at the gathering sported bags or T-shirts warning, "The gender gap will get you."

Smeal told the delegates that the organizing, lobbying and campaigning skills they honed in the ERA effort would build "a movement that's going to change the face of American politics and thereby influence the political life of the world."

NOW is spending $250,000 to test two television commercials and two print advertisements aimed at boosting its membership and its campaign coffers.

"We don't expect every woman in America to send $25 to NOW," the ads all say, "just the 100 million who are discriminated against. And men who care."

In one TV spot, a man's hand puts a gun, a drink and some cigarettes on a table as a woman's voice notes that 11,000 lobbyists represent every interest in Washington.

"But who speaks for women?" the voice asks, as a woman's hand sweeps all the things away. "NOW, the National Organization for Women," the voice says as the hand puts down a NOW button.

Smeal said that NOW expects to have "only a modest impact" nationwide this November but will show "substantial gains" in Florida and Illinois, where ERA's defeat was the most painful. She said women in the Florida Senate are likely to double, from four to eight out of 40.

In Illinois, direct mail is reaching 100,000 ERA backers "to remind them what Gov. James R. Thompson did to ERA," Smeal said.