The mock battle of Florida -- with nothing at stake but bragging rights to the first "win" of the 1980 Democratic presidental campaign -- was winding up today with predictions of a Jimmy Carter victory over forces backing Sen. Edward M. Kennedy (D-Mass.).

From the Panhandle to Miami, phone banks and radio commercials carried pleas to registered Democrats to turn out at Saturday's county caucuses to choose delegates to the Nov. 18 state convention, where a preference poll will measure the strength of the president and his expected challenger.

The routine party exercise was converted into the first major psychological battle of the 1980 wars by draft-Kennedy leaders, seeking to embarrass Carter in his southern base.

But, confronted by a massive mobilization of political forces from the White House, some Kennedy leaders sounded today as if they wished they had never picked the fight.

State comptroller Gerald Lewis, chairman of the Kennedy effort and lone defector from Carter's ranks among the state's Democratic leadership, said, "One can question the wisdom of ever doing this in the first place."

Referring to Mike Abrams and Sergio Bendixen, two disaffected leaders of Carter's 1976 campaign who launched the draft-Kennedy drive in the state and gave it national publicity by their early claims of victory, Lewis said, "I don't think they understood how hard an incumbent president will fight to save his job . . . I wish they'd called it off . . . I'm sure Ted Kennedy would not have picked this as the first battleground."

But Bendixen -- who has put his reputation as a crack organizer on the line in this test -- reaffirmed his prediction that Kennedy will win at least 440 of the 879 delegates to be chosen Saturday.

Carter will nver survive us," he said "As soon as we beat him here on Saturday, his candidacy will collapse all around the country. This is the last confrontation, not the first."

Carter backers, who have maintained from the start that a "victory" for the president would mean getting just over half the delegates, were happy to let Bendixen set the ground rules for press interpretation of what is purely a psychological battle. The Florida delegates to the Democratic convention will be chosen in a primary in March, unaffected by Saturday's or November's results.

"It's all coming together for us," said Jay Hakes, the former Interior Department official who is running the Florida campaign for Carter. "I think we will be able to turn out our people." Hakes has led a huge invasion of Florida by veterans of the 1976 Carter campaign, many recently resigned from Washington jobs. The draft-Kennedy forces have countered with a flood of "volunteers" from points as distant as Arizona and California.

The Carter forces are spending $250,000 and the Kennedy movement about $200,000. But Carter also has unleashed a flood of federal aid to Florida and sent a dozen administration officials and family members in for speeches. This onslaught, plus the help generated by pro-Carter Gov. Bob Graham and the state Democratic organization, has made a Kennedy victory Saturday less and less likely.

Still, the Kennedy forces are fighting in the major metropolitan areas and have filed slates in all but a handful of the rural counties.

The main battleground is in the populous South Florida "Gold Coast" which elects 42 percent of the delegates. Kennedy slates are favored in Broward County (Fort Lauderdale), rated an event bet to win in Dade County (Miami) and given a chance in Palm Beach County. Unless Carter can win at least one of those counties, he would need a near-sweep of the rest of the state, and Kennedy is a threat in Hillsborough County (Tampa) and some of the university towns as well.

The race is complicated by the presence in many counties of a laborbacked "freedom of choice" slate, and by hundreds of independent candidates, supporting Carter or Kennedy, but not included on their "official" slates.

Democratic Party headquarters said today that more than 3,000 persons are seeking the 879 delegates spots. Names are listed alphabetically on each county ballot, and the tally is expected to take hours or even days in the big counties.

Those who win Saturday will constitute just over half the 1,717 delegates to the Nov. 18 state convention here, with the remainder of those slots to be filled by officeholders, party officials and their appointees. Carter is the current favorite of those officials, and should win at the convention, unless Kennedy backers spring a major upset here Saturday.

The campaign in most of the major counties has focused on making phone calls to identified potential supporters and arranging transportation by car or bus to bring them to the single voting place in each county. Estimates of the likely turnout range up to 50,000 people -- still a small fraction of Florida's Democractic electorate.

Both sides have bought radio and newspaper ads in the last few days in hopes of swelling the turnout, but in the absence of actual candidates, most Floridians seem indifferent. In Miami, there has been sharp debate about the Middle East policies of the administration, and here, in the retirement area, Social Security and national health insurances have been argued.

But for the most part, this is purely an organization battle, with most of the visible resources on Carter's side.