The Florida caucuses were a hollow victory for President Carter, a a claimed "win" that really dramatized the vulnerability of his southern political base to a challenge from Sen. Edward M. Kennedy (D-Mass.). They certainly did nothing to discourage a Kennedy candidacy.

At the same time, the caucuses underscored the difficulty of the organizational task facing Kennedy if he tries to unseat the incumbent president. And they left no doubt that Kennedy's personal reputation -- meaning Chappaquiddick, among other thins -- remains a major barrier to his reaching the White House.

While the Carter forces' early claim of a 2-to-1 victory over Kennedy in Saturday's voting for state convention delegates awaited the count from Dade County (Miami), a statewide newspaper poll of Florida Democrats demonstrated how vulnerable Carter may be in the March 11 primary, when Democratic National Convention delegates actually will be chosen.

The poll, taken last week and published today by the Orlando Sentinel Star and three other Florida papers, showed Kennedy and Carter in a dead heat, 43 to 43 percent, with 14 percent undecided. When a third Democrat, California Gov. Edmund G. (Jerry) Brown Jr., was added to the list, it was Carter 39 percent, Kennedy 38, Brown 9, and undecided 14.

That clearly shows Carter vulnerable to an upset in the March primary. While Florida is hardly a typical southern state, it is a key to the region's politics. Its primary is not one the Georgian can afford to lose. The only 1980 primaries to be held earlier are in New England, where Kennedy is favored, and Carter will need to win in Florida to prevent a Kennedy bandwagon from rolling unchecked into Illinois and other industrial states in post-Florida primaries.

Both today's poll and Saturday's voting results, which were closer than the Carter leaders had expected, showed the fragility of Carter's grip on Florida.

"It doesn't please me, but it doesn't surprise me," said a senior White House aide, who added that a private poll in Florida two months ago had Kennedy ahead of Carter.

On the Kennedy side, spokesman Tom Southwick said the Florida results "reinforced (Kennedy's) feeling that a lot of people in all sections share his concerns about all issues and the country's direction."

Carter strategists could take some satisfaction from the performance of their organization. Carter workers, recruited from government offices, law firms and businesses, showed they has not forgotten the skills they developed in 1976 in mobilizing people for a caucus or primary. "Like it or not, said the White House aide, "this is the way presidential candidates are chosen, and we have the people who know how this system works."

Except in Tampa and Palm Beach, Carter carried the counties he expected to win, the ones where he had dispatched his veteran organizers. If his victory in Dade County is confirmed by Wednesday, it will be a tribute to his organization's prowess in an area where the voting population appeared strongly pro-Kennedy.

The draft Kennedy movement, by contrast, was very spotty. Many of the "Kennedy delegates" owe their election primarily to pro-Kennedy unions, particularly the Machinists and the Firefighters, rather than to their own efforts.

In Miami, St. Petersburg and other places, the local Kennedy leadership appeared weak enough to require repairs before the primary. In Florida, as elsewhere, Kennedy's delay in declaring his candidacy and placing his own operatives in charge adds to the organizational challenge he will face if he decides to try to dump the president.

But a far bigger problem is the personal character (or Chappaquiddick) issue, which some optimistic Kennedy lieutenants believed -- on the basis of national polls this past year -- had faded away.

In Florida it has not. Kennedy's 1969 Chappaquiddick accident in which a woman was drowned was a lively topic on the radio talk-shows around Florida the past few weeks, and it was apparently on the minds of many voters.

Today's newspaper poll produced evidence of that. The cross-section of 451 registered Democrats gave Kennedy 52 to 27 percent over Carter in overall leadership ability, and 72 to 14 percent in effectiveness with Congress, But, by 64 to 16 percent, the same voters said they have greater confidence in Carter's moral character than in Kennedy's.

It is clear that, were it not for doubts about Kennedy's character, he would be a near-cinch to defeat Carter in Florida. The importance of those doubts was underlined by the poll's finding that 17 percent of the Carter voters favor him because of their dislike for Kennedy, while 7 percent of the Kennedy voters have a similar personal distaste for Carter.

Interviews with an unscientific sample at the St. Petersburg and Tampa caucuses found many whose main reason for voting was their opposition to Kennedy.

E. T. Wood, a St. Petersburg carpenter, said, "I know the Kennedy family and admire them, but i'm not supporting this one." A voter in Tampa, who declined to give her name, said, "Jimmy Carter is a good man, and Ted Kennedy has a bad record behind him that's not forgotten."

The newspaper poll also suggested the potential of the Kennedy-Carter fight for splitting the Democratic coalition. Blacks, Catholics, Jews and young persons all gave pluralities to Kennedy, while whites, Protestants, middle-aged and elederly Democrats favored Carter. Add that to the character-vs.-competence conflict, and the Democrats have the makings of quite a fight.