BAL HARBOUR, FLA., FEB. 17 -- Organized labor is prepared to withhold endorsement of a presidential candidate throughout the primary election campaign unless a clear favorite emerges, officials said today.

AFL-CIO leaders, gathered for the annual midwinter meeting of the federation's executive council, appeared even more determined to stick to their no-endorsement policy in the wake of the New Hampshire primaries Tuesday.

AFL-CIO President Lane Kirkland said the federation will not endorse anyone unless a majority of rank-and-file union members favors a candidate. So far, he said, no candidate has anything close to a consensus.

"I'm not going to force it," Kirkland said. "I'm not going to invent it."

In the last presidential campaign, the AFL-CIO endorsed former vice president Walter F. Mondale in October 1983 and rode to a landslide general-election defeat with him. "We did what we wanted to do in 1984, and we're doing what we want to in 1988," Kirkland said.

A key political official in the federation said that "unless there's a consensus, I don't think we'll have an endorsement."

The official said the no-endorsement policy could dilute labor's delegate strength at the Democratic National Convention in July but added, "We're just going to have to live with the results."

The official voiced certainty that the Democratic winner will come looking for labor support in the general-election campaign. "I can't imagine they would not want the AFL-CIO support" then, he said.

Meanwhile, the AFL-CIO council unanimously endorsed the proposal by Democratic National Chairman Paul G. Kirk Jr. for a party platform that makes a simple, general statement. The vote was conditional, based on no other group being able to use the platform for a laundry list of demands.

Ratification of the no-endorsement policy here this week reflects the fact that labor has yet to find a candidate around whom it can even begin to build a membership consensus.

Some union presidents have urged Kirkland to endorse someone no later than early May so that labor will not be left out of the selection process. But Kirkland has managed to hold the line against what he considers premature endorsement.

He repeated today that he is prepared to call a meeting of the federation's general board to vote on an endorsement as soon as enough unions indicate that they have a consensus candidate. Under AFL-CIO rules, a candidate must have support of two-thirds of union members to gain endorsement.

Complicating labor's problem is that Jesse L. Jackson, while having nothing close to majority support, is emerging as the most popular candidate among union members.

As Jackson's support builds, union leaders have expressed concern that endorsing another candidate would be even more difficult.

William Winpisinger, president of the International Association of Machinists, said that, no matter who is nominated, Jackson will be a major force in the Democratic Party.

Winpisinger said Jackson will arrive at the party's national convention in Atlanta with "a slew" of delegates. AFL-CIO officials estimate that Jackson may have 1,000 or more by then. (To be nominated, a candidate must have 2,080.)

Although some union leaders have voted to favor a general-statement platform, some expressed concern today that not having a traditional platform would eliminate a way to accommodate Jackson's possible demands in exchange for his support of another candidate.

Albert Shanker, president of the American Federation of Teachers, said this week that the risks of endorsing someone now are very high. "If you're with one candidate, you're very effective unless your candidate loses," he noted.

Shanker said he thinks that chances are very good no labor endorsement will be made until after the conventions. The only way that might change, he said, is if two Democratic candidates are left in the race and labor's endorsement could tip the balance for one.