The top aides for Michael Dukakis and Jesse Jackson, seeking to heal the breach between the candidates, got off to a "good start" Saturday on negotiations to avert a political war and unite Democrats at their national convention.

The discussions, which came only 48 hours before the start of Monday's convention, renewed optimism in the party that Dukakis and Jackson could make peace, perhaps at a face-to-face meeting before the convention begins.Dukakis, the certain 1988 Democratic presidential nominee, and Jackson, the fiery leader of party insurgents, ordered their aides to the negotiating table in a last-ditch attempt to provide the party with longed-for unity.

An agreement would lead to a unified convention; a breakdown could mean an ugly confrontation during prime time and possibly a shattering of black support for Dukakis in his campaign against George Bush.

Paul Brountas, a close friend and confidant of Dukakis', and Ron Brown, the convention chairman for Jackson, appeared highly pleased with their first session held in Brown's 46th floor room of a luxury Atlanta hotel.

Brown told reporters after the hourlong meeting, "We had a very positive meeting and . . . I think (it is) a good start on our discussions."

Brountas, who rushed from Boston for the session, said, "This is a very good start to a convention which I believe will lead to a unified party."

A second meeting, with more aides from the Dukakis and Jackson campaigns, began shortly after 10 p.m. and continued for two hours. Neither side would comment on those discussions.

Jackson rolled into Atlanta as Brountas and Brown were meeting and immediately held a rally. The mass rally outdoors in sweltering heat, which drew an estimated 20,000, capped a three-day journey from Chicago aboard a bus caravan that made stops in Indiana, Kentucky and Tennessee and had the flavor of the civil rights "Freedom Rides" of a generation ago.

Jackson preached his "Rainbow" sermon of inclusion for the young, black, poor, Hispanics and ultra-liberals who turned him into a major figure on the American political scene and told his backers in a slightly hoarse voice he was not about to give up.

"Make this a great Democratic convention," he said. "Hold on. Let's talk. Hold on. Don't surrender your dream. Let's share. Hold on. Don't surrender your dreams. Let's have partnership. I'm going on to the end. I will never surrender. I will hold on."

Susan Estrich, Dukakis' campaign manager, said on CBS television that the way "we're going to win in November is to reach out to Reverend Jackson, to reach out to his excellent staff . . . to reach out to his supporters."

One of the biggest sticking points between the two camps appears to be over platform issues. But Estrich said that while Dukakis wants to keep discussions open, he is reluctant to let the convention endorse a laundry list of issues _ many of them dear to the most liberal wing of the party _ that Jackson wants brought to the floor.

Dukakis plans a triumphal arrival into the convention city late Sunday. He remained in Boston to attend to legislative business Saturday.

A Chicago Tribune poll in five battleground states, released Saturday, showed Dukakis holding a 50-39 percent lead over Vice President George Bush. Dukakis led in New York, California and Illinois and tied the Republican candidate in Texas, Bush's adopted home state. The vice president led only in Florida.

Nearly eight years after he was ousted as president, Jimmy Carter returned to the limelight Saturday flashing his toothy smile and urging Democrats to learn from his 1980 defeat at the hands of Ronald Reagan.

In the center of a shouting throng of reporters during a tour of the Democratic national convention site, the 63-year-old Carter seemed at home and in the heart of his party's politics again.

One reason he lost, Carter said, was the deep divisions in the party stirred by Masssachusetts Sen. Edward Kennedy who challenged Carter for the nomination and waged a bitter party-crippling battle.

Carter said Kennedy hurt him and warned that Dukakis would be hurt if Jackson sits out the campaign and his legions of followers do the same.

He predicted that Dukakis and Jackson would make up their differences and emerge from the convention's last night on Thursday with a united party.

Carter will address the opening session on Monday night before the keynote address by Texas state treasurer Ann Richards. Carter said his talk will be brief.