Eleanor Smeal, who pledged to take feminists "back into the streets," was elected president of the National Organization for Women today, defeating Judy Goldsmith, the moderate incumbent, by a surprisingly wide margin.

The election marked a dramatic comeback for Smeal, who served as NOW president from 1977 to 1982, and an important milestone in the feminist movement's continuing debate over its tactics and direction .

"The leadership of the women's movement and the activists of the movement believe there's a need for a change and for greater activism," Smeal told a news conference. "I think it's time to put a lot more heat on the right wing and the reactionary policies of the Reagan administration."

"We've been good too long," she added. "It's time to go back into the streets and on to the campuses."

Smeal won, 839 to 703, or by about a 10 percent margin. Sonia Johnson, who was nominated at the last minute, received 11 votes. The results were delayed for hours as delegates to the 19th annual NOW conference voted until 6 a.m. today after a problem in the balloting was discovered late Saturday night.

One-third of the delegates had already voted when the problem -- an inaccurate sample ballot -- was discovered, and Smeal and Goldsmith supporters combed the streets of this steamy city much of the night, telling delegates they needed to vote a second time.

Goldsmith, best known for leading NOW firmly into the Democratic Party during the 1984 presidential election, informed Smeal of her victory in a telephone call to her hotel suite at 1 p.m., more than 16 hours after the balloting began.

Smeal supporters greeted the news with shouts, tears, and a chant, "Ellie's Back, Ellie's Back."

Goldsmith later issued a statement congratulating Smeal, and pledging "the full support" of her followers. But many of those supporters were tearful and appeared bitter when Goldsmith addressed the conference several hours later.

She told them, "Be gentle and kind with each other. Be understanding, reject mean-spiritedness."

But Goldsmith indicated that she wasn't about to abandon the debate over the direction of the feminist movement.

"I am not going away," she said. "All of my supporters are here. We aren't going away and we tend to be feisty types."

Observers had believed that Goldsmith, marshalling the powers of her incumbency and supported by a strong slate of running mates, entered the three-day conference here with a narrow lead.

That lead faded, however, as more delegates arrived and Smeal forces organized a sophisticated lobbying campaign, built around charges that NOW had lost members and abandoned the Equal Rights Amendment under Goldsmith's 2 1/2 years of leadership.

On Saturday night, Goldsmith, a former English professor, made a last-ditch attempt to rally support by delivering an uncharacteristically vitriolic attack on Smeal in her final speech as a candidate.

She accused Smeal of waging a campaign of "duplicity," "character assassination" and "hysterical misrepresentation." She charged that Smeal had left NOW "devastated structurally and financially" by leading the organization into an unsuccessful but highly visible campaign for ratification of the ERA.

Goldsmith, widely criticized by Smeal supporters for calling the ERA "an exercise in futility," said that women needed victories, and that she was quietly winning them by making NOW a "multipurpose" organization. She cited the selec -- tion of Geraldine A. Ferraro as the Democratic Party's 1984 vice presidential nominee as an example.

NOW delegates began to vote about an hour later, but the balloting was suspended after 505 votes had been cast because Smeal forces had distributed incorrect sample ballots that officials feared had caused errors in the voting. Balloting restarted an hour later.

Volunteers were dispatched to the nearby French Quarter to notify early voters of the foulup. It was the second wave of NOW delegates to fill the historic spot. Earlier, about 6O conference delegates had marched down Bourbon Street, the main thoroughfare of the French Quarter, chanting, "One, two, three, four, porno out the door. Five, six, seven, eight, pornography is woman-hate."

The antipornography demonstrators were greeted with amusement and shouts of approval as they stopped in front of several striptease places and taped paper plates over pictures of nude women.

"I think it is marvelous, absolutely marvelous," Betty Crout, of Yazoo City, Miss., said as protesters stopped in front of The Silver Frolic Bar, which advertised "topless and bottomless men and women." "I can't think of a better place to demonstrate."

Jim Hardwick, the doorman at the bar, was unimpressed. "A lot of people come in here to enjoy themselves," he said. "It's completely harmless. Everyone on stage , the men and women, have to wear G-strings."

Smeal, who spent a sleepless night awaiting election returns, told convention delegates "I have no doubt" that NOW can reunite "as soon as possible."

But the tone of Goldsmith's remarks Saturday and the divisive nature of the long campaign raised serious questions about that. There were also serious questions about NOW's future relationship with other feminists and civil rights groups.

Goldsmith had carefully cultivated those relationships, and is widely respected among other feminist leaders in Washington. Many regard Smeal as a loner, who can be difficult to work with.

Some also question her confrontational tactics. Smeal built NOW into a 220,000-member organization by waging a no-holds-barred campaign for ratification of the ERA, an issue some feminist leaders consider a lost cause in the immediate future.

She has pledged to revive the ERA as an issue, gather 200,000 women for a march on Washington in support of legalized abortion, launch a television ad campaign, and turn NOW away from its close relationship with the Democratic Party.