President Carter and Sen. Edward M. Kennedy made formal peace tonight, arranging a political reconciliation that will allow the Democratic Party to unite behind Carter's candidacy this fall.

Moments after Carter clinched the nomination tonight, Kennedy offered his congratulations and said he would "support and work for the reelection of President Carter."

"It is imperative that we defeat Ronald Reagan in 1980," Kennedy said. "I urge all Democrats to join in that effort."

Reconciliation came after a day of hectic negotiations that resulted in Carter's strong, though vaguely worded, support of the key provision of the 1980 Democratic platform that Kennedy promoted and the convention adopted over the initial opposition of the president.

This was the Kennedy proposal for a $12 billion jobs program to help fight the recession. Tonight, Carter said, "I accept and support the intent" of the proposal, and said he planned "to pursue policies that will implement its spirit and aims."

But Carter did not mention the $12 billion jobs program specifically, instead promising a new jobs program of his own. And he added: "The amounts needed to achieve our goal will necessarily depend upon economic conditions, what can be effectively applied over time and the appropriate concurrence by Congress."

This passage was part of a detailed statement by Carter that sought to emphasize the points of agreement among various Democratic factions. Carter's brief and gently stated reservations to specific planks that he had opposed were all but overwhelmed by his effusive praise for the platform generally.

On other controversial platform planks, Carter sought to minimize his differences with the Kennedy camp and with feminist activists who also won changes in key planks that the Carter camp had opposed.

The president chose not to mention a new plank the feminists pushed that instructs the Democratic Party to give no aid to any Democratic candidates who fail to support the Equal Rights Amendment. Instead Carter simply said he was pleased the platform reiterates Democratic support for the ERA.

Carter's statement included a personal tribute to Kennedy. "I enthusiastically endorse [the] ideals which were put forth by Senator Kennedy last evenng," the president said, referring to the Kennedy speech that stirred this gathering Tuesday night.

Some of Kennedy's staunchest supporters said they were disappointed that Carter hedged his support for some planks of the platform. Others expressed satisfaction and relief that the president had looked for ways to make peace.

Representatives of organized labor, including key Kennedy supporters, expressed satisfaction with the formulation of Carter's views, and said the president had done enough to merit their support this fall.

Carter's statement was released tonight after a long day of frenetic drafting and urgent negotiations between the Carter and Kennedy camps. The president and the senator talked personally by telephone during the day.

Carter sent his statement to Kennedy to let him read it and offer comment before it went to the delegates in Madison Square Garden. Under a new party rule adopted this week, Carter was required to pledge his support for the new platform and to express any reservations he had with specific planks.

Carter's chief aide for domestic policy, Stuart Eizenstat said that in his meetings Tuesday with Kennedy aides to discuss the statement, the Kennedy side never demanded the inclusion of a dollar figure for a jobs program.

"They did not demand the $12 billion commitment at any time," Eizenstat said. "When we showed them the specific draft language and asked for specific suggestions, they did not make any."

AFL-CIO President Lane Kirkland, at a meeting of his federation's political action committee earlier in the day, said he sees "no choice" but to endorse Carter. He put out the word to union delegates that the Carter statement was acceptable, clearing the way for the AFL-CIO to make its endorsement next month.

Sam Fishman, director of political activities for the United Auto Workers in Michigan and a Kennedy delegate, said: "I feel it [Carter's statement] goes an awful long way in dealing with the apprehensions that a lot of people had abot where the president stood . . . He bought the stimulus plan in principle, with no reservations."

Fishman added: "There is absolutely no notion of protests by walkout. We came here as Democratic delegates . . . We're happy to see President Carter's support for the minority plank. We'd like to see more by way of clarification, but we are basically pleased."

Kennedy delegate Jim Mahoney, executive vice president of the Pennsylvania AFL-CIO and an official of the United Mine Workers, opted for the best possible construction, saying: "We won a big victory. It may not be every last word or syllable that we wanted. But . . . the president accepts and supports the intent . . . I have to take the man at his word."

The president also won the support of a number of nonlabor Kennedy backers, most of them couching their expressions in terms of party unity. Gov. Richard Lamm of Colorado, a strong Kennedy backer, said early in the evening that he felt Kennedy would support Carter actively and that his support would be vital to Carter's reelection. "Kennedy will be there," he said with preannouncement confidence. "The party is an airplane with one wing without him."

But other early Kennedy backers remained bitter and unconverted by the president's platform declaration. Tim Hagan, Democratic chairman of Cuyahoga County, Ohio, and one of the nation's first draft-Kennedy leaders, said: "I congratulate him on his honesty. What he's told us is that he doesn't believe in the Democratic platform. I don't know why we bothered to come. When the nominee can do that, the Democratic convention has no real function."

Rep. Barbara Mikulski (D-Md.), said she was very disappointed with the Carter response. "It totally ignores the specifics of the ERA plank," she said. "The whole thing about jobs does not talk about specifics. I've heard this all my life. Everybody's always for general goals.

"I'm for him with the same enthusiasm that he's for plank three [the $12 billion antirecession plank]."

Former representative Bella Abzug of New York, in contrast, put a more optimistic cast on the same theme. "The important thing on the ERA plank is he didn't make an expressed reservation about it," she said. "We feel he has committed himself and we're going to hold him to it. We women feel we've won a big victory and the degree of support we give Carter depends on how he lives up to his commitment to us."

And three members of Congress who were Kennedy delegates used the opportunity of Carter's renomination day to send him one more threat of restrained support unless he comes around to their way of thinking on a number of issues pending in Congress or awaiting administrative action.

They were Rep. Toby Moffett of Connecticut, Shirley Chisholm of New York and Paul Simon of Illinois.

Disputes over the platform seemed important more for their symbolic value than for their specific policy content. Many politicians here said that the platform won't bind Carter any more than did the 1976 version, which contained several planks that the Carter administration has ignored.

There were two kinds of symbols in this year's platform debate: Symbols that can placate or alienate liberal Democrats, many of them Kennedy supporters, and symbols that could give political fodder to Ronald Reagan's campaign this fall.

The $12 billion jobs program was the most important symbol of the first type. Kennedy pleaded for it Tuesday night, urging that the party reiterate its historic commitment to the poor and unfortunate.

Another economic plank dear to the liberals here and approved in the emotional aftermath of Kennedy's speech declares that the Democratic Party will take no action that would result in increased unemployment.

The plank rquires that all administration economic policies be evaluated by both the Council of Economic Advisers and the Congressional Budget Office. If either find that the proposed policy would cause "significantly greater unemployment," the policy would be abandoned.

The Kennedy campaign drafted this plank as an implicit rebuke to the Carter administration's decision this year to encourage an economic downturn to fight inflation.

In his statement tonight, Carter gently but firmly indicated that he would not endorse this plank. "Responsibility in these matters must ultimately rest with the president and the Congress," and "should not be delegated to staff officials of either branch of government," Carter declared. d

The Kennedy camp also proposed a plank approved on a roll call before Kennedy spoke Tuesday declaring that "the need to guarantee a job to every American who is able to work . . . is our single highest domestic priority," and should take procedence over all others, including the fight against inflation.

Carter, who wants to run this fall as a warrior against inflation, said in his statement tonight that he, too, has "no higher domestic priority than full employment." But he added: "To achieve full employment we must also be successful in our fight against inflation.

When this plank was debated, Carter supporters opposed it on the grounds that it tended to weaken the party's commitment to reduce the rate of inflation.

The other symbolically important planks that the convention approved over Carter administration objections were the work of the women's movement, and one of them alarmed Carter supporters as a potentical liability.

That was the plank that sought to enforce party discipline on the issue of the Equal Rights Amendment. Approved by a voice vote here, the plank says "the Democratic Party shall withhold financial support and technical campaign assistance from candidates who do not support the ERA."

Leaders of the women's movement here said this plank was necessary to demonstrate the party's determination to push the ERA. But Gov. Jim Hunt of North Carolina said the plank was adopted "withou any understanding of what it will take to get ERA approved."

"My state is probably closer than any other state to passing the ERA," Hunt said. "The worst thing you can have is someone telling you what to do from Washington or New York."

Some feminist activists threatened to walk out of the convention if Carter tried to disavow this plank. Instead he ignored it. Aides explained that he saw no need to comment on a convention instruction to the Democratic National Committee. The plank may have little actual effect, however, because the DNC provides minimal support to candidates.

The second plank backed by feminist activists declared, in effect, that the Democrat, would support federal funding under Medicaid for poor women's abortions.

In his statement tonight, Carter said: "Since the beginning of my administration, I have personally opposed federal funding of abortion. I am sworn to uphold the laws passed by Congress, and the Constitution of the United States as interpreted by the federal courts, but my personal view remains unchanged."

This was a way of reminding the convention there is no practical prospect that Congress will soon appropriate federal funds for Medicaid abortions, no matter what the party platform says.

Perhaps because it was the only concrete target for restless political energies in this convention, the platform provoked intense, backstage political maneuvering by numerous interest groups.

A good example was the Campaign for Safe Energy, an active and increasingly effective lobbying group that already had helped push the Democratic Party into an essentially antinuclear-power stance at its June platform hearings.

When they arrived in New York, lobbyists for the group and delegates sympathetic to them concluded that they had been so successful in June that they might not get any attention here. They quickly plotted a way to correct that.

They had one tool to work with, a plank calling for greater federal expenditures on solar energy, which got enough support in the platform committee to be offered as a minority report to the full convention. But the Carter camp quickly accepted the plank, which called for federal expenditures on solar energy research larger than the total of federal support of synthetic fuels research and development.

The Campaign for Safe Energy and its allies then began pressing for an opportunity for one of its allies to speak to the full convention in prime time to draw attention to the antinuclear-power plank, which is inconsistent with Carter administration policy. At first the Carter camp refused, but the group then threatened to nominate its leading ally in Congress, Rep. Edward J. Markey (D-Mass.), for vice president.

Apparently, this threat to spoil the appearance of unity that the Carter camp hopes to promote Thursday night -- when the vice president formally is nominated and Carter makes his acceptance speech -- struck home. When antinuclear activists succeeded in getting many more than the necessary 333 signature on petitions supporting Markey's candidacy, the convention's organizers gave way.