Jimmy Carter made good his boast of last summer -- that he'd beat Kennedy in the battle for the Democratic presidential nomination -- by a simple but effective technique he made Ted Kennedy the issue in the primary campaigns.

It was a low-level campaign that reminded voters of the skeletons in the Massachusetts senator's closet -- the Chappaquiddick tragedy and his marital difficulties. The purpose was two-fold: it took the public's attention away from Carter's dismal record in office, and it was safe from retaliation in kind, since Carter had no known personal scandals that could be dredged up.

The strategy worked, mainly because the press obligingly trumpeted Carter's line that the crisis in Iran and Afghanistan prevented him from debating Kennedy on the issues -- followed later by his announcement that the Iranian rescue fiasco had miraculously rendered the international problems "manageable" enough for him to campaign actively.

This may prove to have been a costly way of winning renomination, however. The personal acrimony between Kennedy and Carter had extended to their campaign staffs and even to their wives, according to my sources. Rosalynn Carter, in particular, is reported to be implacable in her dislike of the Kennedys.

At the staff level, the young Georgians in the White House seem determined to humiliate Kennedy at the convention. Indeed, they've already shown their partisan zeal in the early skirmish over the party platform. In turn, some of the young hawks around Kennedy are angry enough at the Carter campaign tactics to take revenge in the classic Massachusetts tradition -- "Don't get mad, get even."

For their part, the two top Democrats have both had their egos badly bruised. And at their post-primary meeting in the White House, each accused the other of bringing personalities into the campaign.

Carter blamed Kennedy for saying harsh things about him but insisted, "I've never attacked you personally." Kennedy retorted that it had been the other way around: he had run on issues while the president's people had focused on Kennedy's character. "Ive never attacked you personally," Kennedy told Carter.

Now, inside sources say, Carter will try the same technique in the general election, trying to make Ronald Reagan the issue. The president will raise the issue of Reagan's veracity, his alleged irresponsibility, his slips of the tongue -- and of course, his age. Though Reagan's personal life is as spotless as Carter's own, the subliminal message in the Carter campaign, sources say, will be that Reagan is too old and tired to handle the grueling tasks required of a president.