As the Democrats prepare for their Atlanta convention, the foretaste of victory and the liberal credentials of expected nominee Michael Dukakis have muted the often fractious constituencies that make up the party.

But leaders of the constituency groups, sometimes dismissively labeled by their Republican opponents as "special interests" - labor, wom-en, blacks and others - say they will be organized and prepared to do battle for their causes if the need should arise.Dukakis supporters believe they will find little to fight about.

"We always caucus," said Rex Hardesty, a spokesman for the AFL-CIO, which expects to have more than 700 delegates at the July 18-21 convention. "We don't foresee any reason to use it, however."

Women, gay rights supporters, blacks and, for the first time, Arab-Americans, will also be organized and active both on the convention floor and in myriad outside events designed to influence delegates and attract media attention to their causes.

But none of the groups expects any of the bruising floor fights that would allow voters to draw the conclusion the party is in disarray or controlled by a group of far left crazies.

Much of the credit for that goes to the campaigns of Dukakis and Jesse Jackson and the process adopted by the platform committee headed by Michigan Gov. James Blanchard and drafting chairman Rep. William Gray, D-Pa.

It was a process that involved a great deal of private negotiations between and among the interest groups, the campaigns and the Democratic National Committee.

"Everybody was quite reasonable," said Frances Kissling, head of Catholics for a Free Choice, a major abortion rights group. "Our concern was that if other issues were detailed in the platform and went to legislative remedies, we wanted to be included as well. We didn't want to be discriminated against."

Tamar Raphael of the Fund for the Feminist Majority said feminists had won significant victories in the platform process - on retaining the traditional party commitment to abortion rights, to work for passage of the ERA and, for the first time, a pledge for "access to equal endorsement for women and minorities."

Other feminist leaders noted that the Dukakis campaign has a number of women in prominent positions, that has a solid pro-choice rec-ord on abortion and that "people are very enthusiastic about the potential for women in a Dukakis administration."

Hardesty noted a similar restraint in pressuring platform issues on the part of organized labor.

"We've done everything we can to make the process work," he said. "We saw no reason for the platform to go into detail."

He cited as an example that for the first time since the Truman presidency, the Democratic platform will not contain a provision urging the repeal of right to work laws.

"It doesn't mean we're not going to continue working for that," he said. "But we just saw no sense in dragging it in (to the platform)."

One of the tiniest, with 45 delegates, but potenially most explosive of the interest groups that will be active at the convention will be that of Arab-Americans.

Central to its concerns is Middle East policy and an American foreign policy that endorses self-determination for the Palestinian people.

It is an issue that Jackson has campaigned strongly on and has continued to press.

"There has been tremendous pressure to keep it from the floor," said James Zogby of the Arab American Institute. Enough delegates, however, have signed a minority report on the issue to ensure its consideration.

"We were told the sky would fall, the party will be destroyed" if the issue is pursued, Zogby said. "But we will not destroy the party. This issue can be talked about."

He said that while Jackson has not yet decided whether it is one of the issues he will seek to press at the convention, "One way or another, the issue will be in Atlanta."

Outside the convention hall, interest groups and others will also be active.

A coalition, Gay and Lesbian Voice '88, has announced it will be at both the Democratic and Republican conventions, operating an "action center-press room" to track AIDS, human rights and other issues.

Over 100 peace and justice groups, gathered as the Fannie Lou Hamer Convention, have also said they intend to be have a presence on the edges of both conventions, urging the parties to enact an "economic bill of rights" and pressing a "people's platform"

And the militant ACORN - the Association of Community Organizations for Reform Now - said it will hold its national convention in Atlanta to coincide with the Democratic gathering and will aim at highlighting the emergence of low and moderate income citizens as a critical constituency within the party.