Debatable

With so much attention being put on the likely AFL-CIO endorsement of a Democratic presidential candidate next December, something has been forgotten. There will be debates among the candidates before the Iowa caucus and, probably, before the New Hampshire and later primaries that could be just as important as a labor endorsement in determining the winner of the nomination.

Labor may yet have some second thoughts about endorsing anyone. Already some Democratic leaders have passed this warning along to the AFL-CIO higher-ups: ''What if you, say, endorse Mondale? That's bound to antagonize the other candidates who have been seeking your support. What do you think an Alan Cranston or a Senator Glenn or a Senator Hollings or a Senator Hart will do when you go after some bill you feel you need? Isn't it possible that these spurned candidates, all powers in the Senate, might be just a little less inclined to help you out?''

Also, labor leaders are asking themselves: ''What if we endorse a candidate - and he loses out in his bid for the nomination? Won't this be a devastating embarrassment to us, one that, perhaps, we shouldn't risk - sure as we might be that we were endorsing a win-ner?''

The fact is, too, that the union leaders feel no certainty that they can exert an effective discipline over their members in the primaries that would follow labor's endorsement. They saw blue-collar workers moving heavily behind Reagan in 1980. They feel this is less likely to happen in 1984 - but because of the economy and not because of their discipline. But they see a strong possibility of labor's rank and file voting, in large numbers, for a candidate other than Mondale, who now is the favorite to gain the endorsement.

The debates could be terribly important, perhaps decisive. They don't turn on substance so much as atmospherics. Or a candidate saying just the right thing. Reagan, shouting that he had paid for the use of the mike that night and insisting on all of the candidates taking part in the debate, somehow turned the New Hampshire primary in his favor.

Adlai Stevenson was the better prepared, the most articulate in his debate with his challenger Estes Kefauver in 1956 - but somehow the Kefauver demeanor seemed to go over better with many listeners. Or was it merely that the public knew Stevenson - from the 1952 campaign - and Kefauver gained the most because he needed the exposure? Anyway, though Stevenson won the nomination, the Kefauver campaign apparently was helped by this one-on-one encounter.

Ronald Reagan's campaign got a decided lift out of his debates with President Carter, a lift he needed right at the moment. Again, it was Reagan's confident, relaxed manner which gave him the edge - along with the more intense, sometimes almost grim image Carter projected. When Reagan, in a joshing way, turned to Carter after one of Jimmy's verbal jabs and said, ''There you go again,'' he was delivering a knockout blow, although a gentle one - no matter how the debating point score may have finally been totaled by experts.

Mondale is an experienced debater. He clearly beat Dole in the battle of the vice-presidential candidates in 1976. Or did Dole beat himself? The Kansas senator is a master of the sharp-edged quip. He is a put-down artist without peer in the Senate. But the public - again apart from the issues being debated - was less than enchanted with Dole. They found him on the acerbic side. And that's how Mondale ''won,'' or appeared to win.

The best way of determining that Nixon lost the debates to Kennedy in 1960 was that Kennedy, an unknown compared to Nixon, got the visibility he needed out of the first debate to lift him, according to the polls, into the running - and from there to victory. Also Nixon himself said that he ''lost'' the debates and the election merely by accepting Kennedy's challenge.

Here is as good a place as any to say that no one should be too certain that Reagan, if he runs, will, as the GOP nominee, accept a challenge to debate. His chief of staff, Jim Baker, showed in 1980 he isn't going to recommend that Reagan debate unless - or until - it is to Reagan's advantage to do so. So, say, Reagan is way out in front of the Democratic nominee - and stays that way. There simply won't be a debate.

Only if Reagan feels the heat from his challenger - and concludes, as he and Jim Baker did in 1980, that a debate is needed to revive his campaign - will the President give his Democratic opponent that kind of visibility.