The Democratic Party embraced the Equal Rights Amendment today in a bit of carefully staged emotion designed to identify the party with women and their issues.

The "spontaneous" demonstration had been planned for days. And it went off without a hitch. It started promptly on cue as the band struck up the opening notes to "I Am Woman," and lasted exactly 14 minutes, just as planned.

Virtually the entire leadership of the party, including seven 1984 presidential hopefuls, took part.

Delegates waved colorfully printed placards, saying, "ERA is a Democratic Issue," "Women Are the New Voting Bloc," and a "New Era for ERA" as the band played "The Battle Hymn of the Republic" and "God Bless America."

It was timed to fit in between a series of speeches by presidential aspirants, and designed to draw a clear distinction between the Republican and Democratic parties at a time when women are showing widespread disillusionment with the GOP and President Reagan.

It also was a symbolic acknowledgement by party elders of the importance of women as voters and party leaders. Women have made up 50 percent of the delegates to national Democratic gatherings since 1978, but never before have they been as integrated into the party's leadership.

"I don't know quite how to act," said one feminist. "This is the first time I've come to one of these things where I didn't have to organize a demonstration against the party, or steal credentials to get in."

Rep. Barbara A. Mikulski (Md.) said, "I think Ronald Reagan has made it a whole new ball game for women in the party. We're more under attack than ever before."

Today's demonstration came a day after ERA leaders formally conceded that the amendment will reach its June 30 deadline three states short of ratification.

At the same time women here have begun a subtle, but highly significant reshaping of their agenda. The clearest sign of this was a series of amendments drawn up by women members of Congress to a statement of party goals being written here.

The amendments mention the ERA almost as an afterthought, simply saying, "We will not abandon ERA." Instead, they focus on a series of very practical economic issues, such as equal pay and pension protection for women.

Mikulski said she believes these issues will attract many women "who didn't think the equal rights issue was their cup of tea."

"One of my concerns is that the right wing has stolen our issues of family, neighborhood and crime," she added. "I want to get them back."

The pay equity issue is at the heart of this effort. "Today there is frustration among the millions of women who have entered the workforce in the last 10 years and are still earning 59 cents for every dollar a man earns," Lynn Cutler, a Democratic congressional candidate from Iowa, said in a dramatic floor speech before the demonstration.

The only undercurrent of uneasiness among women delegates here is that the party will give them only token symbolic recognition. "Let's make sure the party listens and hears us," Rep. Geraldine A. Ferraro (N.Y.) told a meeting of the party's women's caucus.

This is expected to surface openly Saturday when Eleanor Smeal, president of the National Organization for Women, and supporters plan to picket the convention to protest Democratic state legislators who voted against the ERA.

The actions of women here are part of an ongoing battle for the soul and resources of the party that is being waged without fanfare by blacks, labor, women, and Hispanics.

In varying degrees, all complained in caucuses during the last two days that they don't have enough say in party affairs. The most pointed example of this was a resolution passed by the black caucus that condemned the party for dragging its feet on issues of concern to blacks.

The resolution, authored by Rep. Gus Savage (Ill.) said, "This party's action on the national level has failed to match its advocacy, even though its advocacy has been insufficient to the need to substantially and immediately alleviate the gross discrimination suffered by blacks in the United States."

This same frustration was expressed in a meeting of the Hispanic Caucus.

"We still are not considered a power in the Democratic Party," said Jack Otero, a vice president of the Brotherhood of Railroad and Air Clerks. "We're still getting the crumbs from the table."