Sen. Edward M. Kennedy's 2-to-1 lead over President Carter in public opinion polls appears to exaggerate his potential strength as a presidential candidate, a Washington Post poll indicates.

Much of Kennedy's support, the poll suggests, comes from people who hold positions on issues that are almost diametrically opposed to the positions held by the Massachusetts senator.

If he became a candidate, a good bit of that support could be expected to disappear. Nonetheless, Kennedy would still hold a sizable lead over the president at the outset of any contest between them.

Twenty-three percent of those polled supported Carter and 46 percent supported Kennedy. But Kennedy was favored by an even higher percentage of people who want to cut taxes, get tough with the Soviet Union and slow down the pace of integration.

Kennedy, an outspoken liberal, also outpolled Carter by 22 percentage points among those who called themselves conservative Democrats.

Another indication that Kennedy's popularity is unrelated to issues came over the question of a government-sponsored health program. Kennedy, the author of legislation for national health insurance, polled as well among people who oppose such a program as among those who favor one.

Polling authorities offer three explanations on why issues have such little bearing on Kennedy's standing in the polls: voters don't care about the issues that separate Carter and Kennedy; voters haven't focused on the issues, and, most important, Kennedy's celebrity status, and the image of Camelot it invokes, overrides other considerations.

"Teddy Kennedy is a movie star. People are responding to him just like they would to Jimmy Stewart or Robert Redford," said Gary R. Orren, an associate professor of government at Harvard University who assists The Post in its national polls.

"There's an artificiality to his lead," Orren added. "There would be an erosion if he were subjected to the rigors of a campaign."

That same statement, in only slightly different form, was echoed repeatedly in interviews with a series of the nation's leading political pollsters, academics and campaign consultants, including those who worked closely with the 1976 campaigns of Ronald Regan, Gerald R. Ford, and Jimmy Carter.

Just how much erosion is uncertain. "Right now, Kennedy has the best of all worlds," said Robert Teeter, a respected Republican pollster. "He can pick his issues. He can do it without answering any of the negatives. In a campaign it would be a different situation."

Nevertheless, he said, "my inclination is that Kennedy would beat Carter if they went head to head."Kennedy has consistently said he won't be a candidate for the 1980 Democratic nomination if Carter runs. But polls by George Gallup, Louis Harris and other organizations have shown him to be favored over Carter about 2 to 1, a finding similar to that of the new Washington Post poll.

In addition to finding that Kennedy gets support from people who seem opposed to him on issues, The Post poll found Kennedy benefits from a backlash against Carter's handling of the nation's economic and energy problems. More than half of the Democrats interviewed in the survey gave the president a negative rating on both counts.

Kennedy was favored 82 to 12 percent over Carter by those who don't like the way the president has handled the economy, and by 79 to 16 percent by those who disapprove of his energy policies.

Carter outpolled Kennedy 60 to 39 percent among the minority who like his energy programs, and by 61 to 37 percent among those who approve of the way he has handled the economy.

Carter's perceived successes in foreign policy, however, haven't helped him much, according to The Post poll. It shows that 62 percent of those interviewed think he is doing a good job in this area, but this same group favors Kennedy as a presidential candidate, 55 to 43 percent.

The president has similar problems among those who think highly of his overall performance. Among those who give Carter an overall job rating of seven on a scale where 10 is ideal, only 30 percent favor his reelection over Kennedy.

This hits at the heart of Carter's problem with Kennedy. Simply put, the president is judged harshly on his perceived failures, but he is not getting political credit for his successes. Kennedy isn't judged by the same standard. The Post poll indicates. White House aides have said as much for months.

The Post's findings were part of a larger poll of voter attitutes toward the 1980 race. A total of 1,808 persons were interviewed by telephone in the poll. Of that total, 750 identified themselves as Democrats.

Carter's position in the polls, of course, may change by next year. Few things are as fluid as presidential politics, or the American public's fickleness in judging its presidents. Then, too, ther are few solid signs that Kennedy intends to become a candidate.

It is also instructive to note that a July 1975 Gallup Poll found Kennedy leading the next highest Democratic presidential contender, Alabama Gov. George Wallace, by 27 percentage points, and then President Ford by 24 points. a year later, Jimmy Carter of Georgia, who didn't even register on the 1975 poll, was the Democratic nominee for president.

Many political scientists hold that presidential races are decided on the judgment voters make of the record and leadership of the incumbent, and not on the promises of the challenger. This currently works against Carter. The complaint most voiced about him by those polled was that he was a poor leader. Among those people interviewed who said they place a premium on leadership, Kennedy outpolled Carter, 3 to 1.

Kennedy also has an unusually strong base among influential groups in the Democratic Party. In Post interviews of Democrats, he outpolled Carter 70 to 27 percent among liberals, 71 to 28 percent among blacks and 74 to 23 percent among union members and their families.

Kennedy is a liberal and has been closely identified with positions favored by organized labor and civil rights groups.

It is more difficult to understand why he outpolls Carter among those who think of themselves as conservatives. Kennedy, for example, outpolls Carter 5 to 1 among persons who think racial integration is moving too fast.

Although Kennedy repeatedly has challenged Carter's efforts to control government spending, Kennedy outpolls the president 52 to 18 percent among those who think taxes should be cut even if it means puttign off other programs, and 57 to 38 percent among those who think the government must have a more balanced budget even if that means spending less money on health and education.

"Kennedy's appeal is not related to issues," says Republican pollster and strategist Teeter. "It's a personal perception. And in politics, perception is reality."

"There is a mystique about him. He has inherited it," says Seymour Martin Lipset, a Standord University sociologist and political scientist. "It's the family thing, the glamor, the assassinations, everything. Plus, it has been clear for a long time that most people think the country is in real trouble."

"There's a feeling that we've had bad leaders for some time. Nixon, Johnson and Carter are all regarded as disasters by many people," he added. "What people are looking for is a leader. So when they do this they return to the Kennedy years, and the aura about the Kennedys."

Richard B. Wirthlin, Republican Ronald Reagan's pollster, says: "The bottom line is that people vote on their feelings toward a person rather than how they line up on issues, especially at this stage of game. But there's no doubt in my mind that Kennedy's support would be narrowed considerably if he became a formal candidate.

"You have to remember the same thing that benefited Carter in 1976. Those who were most confused on where he stood on issues were his strongest supporters." CAPTION: Picture, Carter and Kennedy: Senator leads president 2 to 1 in polls, but there's an "artificiality to his lead." By Gerald Martineau - The Washington Post