Near the soul-searching hour of 11 p.m. Saturday, Rep. John Conyers (D-Mich.) stepped under the strobes to introduce the Rev. Jesse Jackson. The congressman shouted about the historic bid by a black for the presidency this year, defined the "New Politics" of change and cooperation among the black leadership.

And, very subtly, he praised Jackson for his understanding about frictions of the past.

"What a difference a year makes," observed Conyers, above the cheers of the 3,000 who were overflowing the ballroom at the Washington Hilton for the annual Congressional Black Caucus weekend. "Those 12 months have propelled black politics into history."

Jackson, who went the distance from the Democratic primaries to the convention to compete for the presidential nomination this year, followed Democratic presidential candidate Walter Mondale to the podium Saturday. Both were cheered. Both talked about the need for a strong black voter turnout next month.

"We must have a change, a change from a Reagan administration to a Mondale alternative," said Jackson, hoarse from a day of preaching and campaigning.

After shouts of "We want Fritz," Mondale reminded the crowd, "This election is not about jellybeans and pen pals. It is about old folk who can't afford medicine. It is not about sending a teacher into space but about educating our children. It is not about the Republicans sending hecklers to my rallies but about Jerry Falwell picking the next justices of the Supreme Court."

In what had become a pattern for the long weekend of intense politics, the crowd stood up several times, applauding, whistling and collectively crossing their fingers for Jackson and Mondale. But the rally for the Democratic point of view, the repeated reminders to invest the black vote in black children's futures, and the robust acknowledgment of Jackson's power was only one difference Conyers was describing.

Last year at the same event, the largest black political gathering during the year, Jackson was not introduced to the crowd. It was not quite a snub, but the discussions of his presidential bid had opened heated divisions between the 21-member caucus and other black leaders. This year marked an emotional and pragmatic peace treaty with Jackson, who received 85 percent of the black vote and 22 percent of the white vote in his primaries. He was hailed by speakers throughout the weekend gathering as champion, prophet, friend and adviser. Speaking at both the caucus' prayer breakfast and dinner gala, he discussed forgiveness and history, saying, "Our people are not mean when they reject freedom."

As the night wore on, Rep. Mickey Leland (D-Tex.), an early Mondale supporter, talked about his endorsement's fallout at home. "No question it cost a lot of pain and frustration," said Leland. "My popularity diminished but not my base of support. In leadership you have to make some untasteful decisions. I don't regret the decision because Mondale needed some black leaders of integrity."

The spotlight on Jackson, and his selection as recipient of this year's Adam Clayton Powell award, was seen by many as compensation for the friction of the past. "I was deeply disturbed last year. So we do what you always do in politics -- overcompensation," said Conyers.

Both Democrats and Republicans said the spirit and agenda raised by the Jackson campaign should be continued. "We can't be lost again," said Gloria Toote, an adviser to the Reagan-Bush reelection effort. "This new focus brought about by Jackson -- and I was a financial contributor -- we can't let die." Added Rep. Ed Towns (D-N.Y.), another supporter of the Jackson candidacy. "It is important for all of us to come together. Jesse Jackson has probably saved the Democratic Party."

However, the "New Politics" still allows some room for new disagreements. In his speech, Jackson advocated voting along racial lines for the black politicians running in November. A definite uneasiness could be felt in the room. "There are seven more House seats that belong to us. We are more concerned about buddies than brothers and sisters." Privately there were grumblings about playing the coalition-building game and, Conyers said, "We can't be the point men on this."

During the five-day round of meetings and cocktails that netted the Caucus Foundation $1 million, the heart of the discussions was political, not peripheral, and the majority of gatherings were workshops -- 18 brain trusts and more than two-dozen issue forums, not tableaux of flying business cards and flashy fashion.

Early on, giving the Distinguished Lecturer address, Charles Hamilton of Columbia University, described the need to address the "New Normalcy." That, he said, is the "center-right" orientation of the major political parties, and the private-sector economy that he analyzed can prosper without full employment. "Social policy must come to terms, first and foremost, with employment, work, income-earning activity," said Hamilton.

But political participation overrode the economic discussion with a division over the November election. Ronald Walters, who was a chief adviser to Jackson, said he advocated a write-in vote for Jackson to counteract the "weak position" blacks experience at the beginning of each administration. Nate Holden, a former California state senator, echoed what Jackson himself would later say: "You can go fishing because you can spend $100 a day at the Washington Hilton, but the majority of black people cannot afford four more years of Reagan."

Del. Walter Fauntroy (D-D.C.) emerged from the forum on Haitian refugees with a request to have an emergency session on human rights violations in the Caribbean nation. "I am planning to take a delegation to Haiti in December and then we will consider the hearing," said Fauntroy. "In the meantime we have attached an amendment to the continuing resolution to have the administration demand steps toward establishment of political parties and free elections before any more aid" is sent, he said.

But there were the traditional pauses for parties and song. Music ranged from a duet by Fauntroy and vocalist Jean Carn, the soothing dinner accompaniment of Arthur Prysock, a high life band from Liberia at one reception, to Branford Marsalis playing quietly at the CBS Records party at the Four Seasons and competing with the driving disco of "Somebody Else's Guy" across the hall, and gospel plus gospel.

Church's Fried Chicken gave a reception for Dorothy Height, the venerable adviser to presidents and the president of the National Council of Negro Women. Church's president Richard F. Sherman announced more commitment to minority interests and a few black Republicans were doing some business and political crossover work.

In one corner, Melvin Bradley, special assistant for policy development at the White House, and Gloria Toote, briefcase in hand, were talking about a new survey that showed 20 to 28 percent of registered and unregistered black males, aged 18 to 24, favor Reagan. "My personal interpretation is that young blacks have not been brainwashed. It is their preference to be different and to choose their own future. They also like Reagan's male image and he talks about an America where they will achieve with maximum efficiency," said Toote.

When each woman entered the Anheuser-Busch reception, she was given a long-stemmed yellow rose. When Rep. William Clay (D-Mo.) stepped into the spotlight, he received a large sketch of himself marking his 25 years as an elected official. Later at the dinner he received an award from his colleagues.

At the CBS Records bash, decorated like a scene from "Casablanca," Rep. Alan Wheat (D-Mo.) said Mondale was leading slightly in a poll of his district. "Forty-two to 40. It shows people agree with what Mondale says," said Wheat.

And yesterday, at the crowded brunch given by Rep. Charles Rangel (D-N.Y.), he talked freely about considering a run for mayor of New York. On Friday Basil Patterson, a former deputy mayor of New York, considered a natural consensus candidate to challenge Mayor Edward Koch next year, withdrew from consideration. Yesterday Rangel said he was planning consultations this week in New York, and said, "I think it would make sense" to move on and bring younger politicians into Congress.

A scheduled celebrity tennis match, sponsored by Black Entertainment Television, was cancelled because of rain, but the celebration went on with pros Leslie Allen and Zina Garrison and actor Roger Mosley dropping in on other events. Olympic gold medalist Ray Armstead was also mingling with the crowd in his red jogging suit and his medal for the 4 by 400 meter relay.

All over the House office buildings and the Hilton headquarters, groups were clustering on new political thrusts. A bipartisan group was working on The Millennium Society, which would finance and develop a black political strategy. Carol Adams of Loyola University was circulating a survey on black women elected officals. Janette Harris, a professor at the University of the District of Columbia, was buttonholing guests about Professional Women for Mondale-Ferraro. Fast on her heels was Donna Zaccaro, daughter of the vice presidential candidate Geraldine Ferraro, saying "people are supportive out there."

Throughout the weekend the concerns of the black family and black women were showcased. The call to form a nonpartisan group with a political action committee component, tentatively called the National Black Women's Political Caucus, was issued by former New York congresswoman Shirley Chisholm. The incentive, she said, came from the founders feeling slighted by the absence of a black woman on the vice presidential possibilities list and feeling angry at the exclusion of some issues at the convention.

California State Assembly member Maxine Waters, former Pennsylvania secretary of state C. Delores Tucker, and most of the women labor, religious and education leaders at the weekend gathering, responded positively to the meetings. A breakfast the group held yesterday was expected to attract 600 people but almost 1,000 showed up for rolls, coffee, and plenty of sisterly preaching.

Tucker announced "trickle-down politics" had ended. Getting one of the last standing ovations in a long weekend of cheers, Chisholm sounded another lesson of "New Politics": "Black women have been part of coalitions, we have been one of the most loyal segments but no one gave us respect. In this country we have learned you become respected when you exert leverage."