CHICAGO, AUG. 1 -- It was the kind of gathering where Bruce Babbitt could draw boos for saying, "Marxism is a dying ideology."

The 1,200 organizers and activists for peace, environmental, feminist and consumer groups in some 25 states and their trade union allies meeting at an airport motel here this weekend represent the left-wing of activism in the Democratic Party. Their reputation as energetic grass-roots workers is such that in the first 15 hours of their gathering, six of the eight Democratic presidential hopefuls came by to recruit support and the other two sent their regrets that schedule conflicts kept them away.

Jesse L. Jackson, who drew perhaps the most full-throated cheers with his talk this morning, jeered at those in the Democratic Party who warn it should avoid the "special interests" represented in the room. Listing the causes that have attracted the organizers of the left, from stopping aid to the Nicaraguan contras to enacting plant-closing notification laws and the Equal Rights Amendment, Jackson said, "Those 'special interests' are the Democratic Party.

"I would rather run to the special interests as a Democrat than run from the special prosecutor as a Republican," he said, to a chorus of cheers and whistles.

The other five who appeared before the group Friday night or today -- Sens. Joseph R. Biden Jr. (Del.) and Paul Simon (Ill.), Rep. Patricia Schroeder (Colo.), Massachusetts Gov. Michael S. Dukakis and former Arizona governor Babbitt -- tried in their own ways to establish rapport with the activists.

Babbitt took the risk of saying things he knew they would oppose, and drew some boos and hisses, but ended with healthy applause.

He reacted good-naturedly when his first reference to a "universal needs test" for entitlement programs drew boos, promising to "turn you {skeptics} around."

Arguing that the Democrats' first test is a "realistic" budget-balancing strategy, Babbitt said his party has to be willing to write farm laws "that protect the family farmer in the Midwest but don't send $10 million checks to agribusinesses in California" and housing laws that "help young couples afford their first home but don't subsidize ski condos in Colorado" and to tax Social Security payments above certain income levels "so we don't treat the Mellons and the Rockefellers the same way we treat a widow in a cold-water flat."

By the time he finished with proposals for "workplace democracy" and "a uniform national day-care voucher," he was getting standing ovations.

Simon, who, like Jackson, had spoken at several previous "retreats" sponsored by the Midwest Academy, a Chicago-based training center for community organizers, was well received from beginning to end of his speech. He was cheered for his boast that he is the only candidate who "voted against every single one of the tax bills that have cut the tax rate on the wealthiest Americans in the past six years from 70 percent to 28 percent."

And he was cheered again when he promised that "if I am president on Jan. 21, 1989, I will immediately contact {Soviet leader} Mikhail Gorbachev and say, 'If you're willing to stop nuclear tests, I'm willing to stop nuclear tests.' "

Schroeder, who had the tough assignment of following Jackson this morning, got off some lines that seemed to surprise and delight the left-wing audience. The Denver lawmaker, who has said she will decide in September whether to seek the 1988 presidential nomination, went beyond her standard call for "a rendezvous with reality," by saying, "The American people don't want to be diddled any more. They want something real."

Schroeder also suggested that President Reagan has done the nation a disservice because he "redefined Americans as winners." People who met failure or disappointment in their lives, she said, "were ashamed and didn't even feel like Americans, and it's increased the suicide rate and driven people to drugs." The administration's only answer, she said, raising her voice an octave to a falsetto range, "is, 'Just say no.' "

Biden and Dukakis delivered variations of their standard speeches. Biden, emphasizing his foreign-policy credentials, also played the generational theme. Facing a hall full of organizers mainly in their 20s or early 30s, he said, "The world is ready for a new activism. I get criticized by the press for talking about generational politics, but the hell with them."

Dukakis told the story of Massachusetts' economic recovery and ticked off his opposition to aid to the contras and the reflagging of Kuwaiti tankers. But unlike Biden and Babbitt, who stayed around after their Friday evening speeches to mingle with the activists and recruit workers, Dukakis was in a hurry to get home.

"I've been campaigning eight straight days," he said, "and I've got to get back to Boston."

Babbitt, within earshot, said, "You go back to Boston, governor, and stay just as long as you want."