In a stunning reversal of political fortune, Sen. Edward Kennedy swept to strong upset victories over President Carter tonight in the New York and Connecticut primaries.

Kennedy -- his presidential prospects seemingly buried just last week by a landslide defeat in Illinois -- dug out in a big way tonight with the help of overwhelming margins from Jewish voters who are unhappy with the administration's vote in favor of an anti-Israeli resolution in the United Nations Security Council and with Carter's subsequent attempts to explain his position.

Tonight Kennedy won not only important delegates but also the prospects of a new round of contributions for his financially crippled campaign.

With 99 percent of New York's precincts reporting, Kennedy had 59 percent, Carter 41 percent. With all the votes counted in Connecticut, Kennedy had 47 percent, Carter 41 percent.

The results left Carter with a commanding lead in the overall delegate count. United Press International estimated that Kennedy would win 164 delegates in New York and 29 in Connecticut for a total of 193, while Carter was estimated to have won 118 in New York and 25 in Connecticut for a total of 143. UPI estimates that Carter now has 747 1/2 delegates to Kennedy's 399 1/2.

Carter's concession of defeat was handled for him by campaign manager Robert Strauss.

"I think there was a great deal of protest here in this vote," he said tonight. He explained: "It was a confluence of a lot of negatives.We have not had a piece of good news for the last 10 days." Strauss cited the administration's recent budget cuts and the U.N. resolution, saying: "The U.N. resolution we did not handle well. That was a mistake, and it hurt us."

Carter's pollster, Patrick Caddell, said that in New York doubts about Kennedy's morality and honesty ceased to be factors in the voter decisions, according to his own surveys. This was in some contrast to the other states, where voters were saying that these were indeed concerns.

Instead, Caddell said, Kennedy ceased to be the issue, and it became a question of whether or not the voters approved of Jimmy Carter. "It became Carter vs. Carter," he said, "just like it was in 1976." And, just as in 1976, Carter finished poorly in the New York primary. He finished fourth the last time.

Carter's landslide defeat of Kennedy in Illinois convinced New York voters that Kennedy was not a viable candidate, Caddell said, and it actually made it easier for New Yorkers to view this primary as a referendum on Carter. The structure of voter attitudes in Connecticut paralleled that of New York, Caddell said, with Connecticut always rating Carter about 8 to 9 points better in the surveys.

Caddell said that both states bear little similarity to those of the Midwest. For example, he said, Catholics in the Midwest share a basically Protestant ethic, unlike Catholics in New York and Connecticut.He said that Kennedy's position on abortion actually helped him in New York, rather than hurting him as it did in most states.

In New York, Jewish voters accounted for about 38 percent of the statewide vote, according to interviews by NBC News of voters leaving the polls. Kennedy swept the Jewish vote by a 4-to-1 margin, according to the network survey.

Kennedy defeated Carter in New York City -- which had close to 60 percent of the state's votes -- and in its surrounding suburbs by about 58 to 39 percent, according to the ABC News exit polling.

Carter won in only one area of the state, industrial upstate cities, including Buffalo. There Carter had 62 percent of the vote to Kennedy's 37.

New York's Catholic and black voters split their ballots fairly evenly between Kennedy and Carter, according to the network exit polling.

The Massachusetts Kennedy family has long had strong political ties to Connecticut, which gave overwhelmingly enthusiastic support to John F. Kennedy's 1960 presidential campaign, and now played a similar role for the candidacy of his last surviving brother. Jews in Connecticut also voted overwhelmingly for Kennedy, but they constituted only an estimated 12 percent of that state's vote.

Kennedy's wins in New York and Connecticut still leave him far behind Carter in delegates. White House press secretary Jody Powell has estimated that Kennedy will need to win 60 percent of the delegates from now on in order to take the presidential nomination from the president.

Carter manager Strauss left open the possibility that the president may now abandon his strategy of staying in the White House instead of actively campaigning. Asked if Carter would be coming out to campaign, Strauss said: "Not in the next week or 10 days. Whether . . . in Pennsylvania, I don't know."

Pennsylvania's April 22 primary, with 185 delegates at stake, marks the next major test for the two candiates, Stauss said. He predicted that Carter would defeat Kennedy in the April 1 primaries in Wisconsin and Kansas and in the April 5 primary in Louisiana.

"We were hurt by the president's inability to campaign," Strauss said. "And Sen. Kennedy put on a better campaign than he has done."

Strauss added: "It's a damn sharp dip in the road, but it's not more than that. We have a lot of delegate leverage on him. And Wisconsin and Kansas and Louisiana will add to that."

Strauss said he and pollster Caddell had told the president two days ago that he "might lose" New York. He said he was more surprised by the defeat in Connecticut, saying, "I thought we'd win it by six or seven points."

On Sunday, Vice President Mondale appeared at a dinner in New York City attended by prominent Jews and was roundly booed virtually every time he mentioned Carter's name or the president's commitment to the security of Israel.

The president also won little support, according to both the polls and interviews, from New Yorkers concerned about interest rates and inflation rates that are nearing 20 percent, and about Carter's planned budget cuts, which will have a sizable impact on New York City.

Carter did enjoy in New York and Connecticut the strong and solid support of most elected Democratic officials.

In Connecticut, Carter had strong early support from Gov. Ella Grasso and of most of the state's Democratic mayors.

In New York, Carter had the equally enthusiastic support of New York City Mayor Edward Koch, Lt. Gov. Mario Cuomo, Democratic Party Chairman Dominic Barranello, and most of the New York City ward bosses. Gov. Hugh Carey remained neutral -- but Carter made good use of the governor nevertheless, running ads that showed Carey praising Carter as he signed the New York City aid bill on the steps of City Hall, with Carey saying New Yorkers would never forget Carter for the aid he has given them.

Carter was not helped by the publication in the New York Daily News of polls by Louis Harris during the last week of the campaign. In a poll based on interviews conducted last Tuesday and Wednesday, Harris said that Carter was leading Kennedy statewide by 61 percent to 34 percent, with just 5 percent undecided -- a figure that both Carter and Kennedy strategists believe was far too low, considering the displeasure of the Jewish voters with Carter and their disinclination to support Kennedy because of doubts about personal morality and honesty.

But a few days later, based on interviews conducted Saturday and Sunday, Harris detected what he called a shift from Carter. His poll showed Carter at 56, Kennedy at 36, with 8 percent undecided -- and in New York City, Carter was leading Kennedy in that poll by just 6 points. "All the movement is now away from Carter," Harris told New Yorkers in a bylined story about his poll, which appeared in the Daily News on the day before election.