The moment Sen. Edward M. Kennedy became available, President Carter's operatives began to warn key party leaders that a Carter-Kennedy fight would tear the Democratic Party asunder along religious, sectional and political lines -- a warning that immediately began undermining its own purpose.

Carter's hardball originated with top aide Hamilton Jordan and his political deputies. It boils down to this: Jimmy Carter is in the race to stay; if you join Kennedy against him, you will rip the national fabric -- besides contributing to a Democratic blood bath. And make no mistake; we'll be observing closely who is for us and who is against us.

The intent clearly was to prevent a stampede toward the Kennedy bandwagon. But the reaction has been overwhelmingly negative. Carter's hardball response is interpreted by longtime Democratic politicians as an indication that the president and his men have no interest in a post-Carter Democratic Party but are content to bring down the temple as they leave it.

Kennedy's changed tune brought neither surprise nor melancholy from the West Wing of the White House. Carter's closest advisers -- especially Press Secretary Jody Powell -- long have been convinced that Kennedy would challenge him. To them, Kennedy has simply cleared the air, thus triggering what obviously was their previously planned strategy.

That strategy closely resembled the "full-court press" of the old Nixon days: putting out the word in the most unmistakable terms possible. At the White House, prominent Democratic politicians were warned by Jordan himself that a bloody battle would result if they backed Kennedy. But bloody or not, Carter would win. Jordan's mood was described as "macho," more swaggering than regretful.

Jordan's operatives simultaneously were on the telephones to pound home a slightly different message in explicit terms. One warned Democratic politicians in the Northeast, naturals for defecting to Kennedy, with these blunt words, seemingly read from a prepared script:

A Carter-Kennedy shoot-out will divide the Democratic Party and the nation "worse than Vietnam. It will be North v. South. Protestant v. Catholic. The emotional level will rise during the next two months."

He next warned of the consequences of a Kennedy nomination: "In a general election, he's going to get clobbered. Wait 'til the Jesse Helmses of the world get ahold of him. He won't carry a state below Kentucky."

This Jordan agent stressed Carter's tenacity, retelling the oft-told story of how he ran again for governor of Georgia in 1970 (after losing in 1966) against Jordan's advice. Finally, the big and slightly bullying pitch: "Over the next two months, we'll be finding out who our friends are."

The impact was highly negative. One visitor went straight from the White House to a pro-Kennedy leader's Capitol Hill office to brief him. Others wondered about talk of Protestant v. Catholic fratricide, when Carter must contend with Kennedy for Catholic voters in the important early delegate tests in Puerto Rico, Iowa, New Hampshire and Massachusetts.

The abrasive tone confirms the interpretation of that unfortunate remark by the president's mother, in Nashua, N.H., Sept. 9. When she publicly raised the possibility of a third Kennedy assassination, after having uttered the same thought in private statements earlier that day, it was widely interpreted in the political community, fairly or not, as White House orchestration.

While claiming Mrs. Carter's comments were only a mother's musings, the president's men feel hardball can serve two purposes: keep wavering Democrats out of the Kennedy camp, and show Teddy Kennedy he cannot hope for a Carter withdrawal (and therefore might well reconsider entering).

Party stalwarts, many personally fond of Carter, believe that is the route to disaster. They feel no sense of danger from the exaggerated powers of a weak incumbent president. They contend Carter would have been better advised to stress foreign policy and integrity and to hope that somehow, Kennedy would back out in the end.

Ham Jordan's hardball confirms suspicion among these stalwarts that the Carter team has never been more than a temporary occupant of the Democratic structure, ready to burn it down in the event of an eviction notice. The fear rasied by these calls concerns not so much what candidate Carter can do to them in his quest of the nomination but what a lame-duck president might do to his party if Kennedy is nominated.