The campaign that is just ending became in its last days a battle for turnout. That hasn't been true in other recent campaigns. In the negative, pessimistic climate of the recent past, candidates often assumed they couldn't do much to increase the enthusiasm and turnout of their followers, and they concentrated instead on diminishing enthusiasm and turnout on the other side. Candidates' speeches concentrated on opponents' liabilities: Jimmy Carter's weakness, Ronald Reagan's inexperience. Television spots attacking opponents' mistakes were beamed into areas where his party was traditionally strong.

You didn't see such tactics so much this year. Ronald Reagan in debates and in his 30-second and 5- minute spots, spent surprisingly little time excoriating Carter-Mondale inflation or setbacks abroad. Instead, Mr. Reagan emphasized the America he claims he has made "better, stronger, prouder." Even challenger Walter Mondale in the last 10 days of the campaign concentrated on making the positive case for his kind of Democratic politics, on the need for compassion for the weak at home and for efforts to reach agreements with our adversaries.

Both candidates talked explicitly about turnout, Mr. Reagan warning against overconfidence, Mr. Mondale against overreliance on the polls. But more than their warnings, their emphasis on positive messages indicated that both sides wanted to motivate their supporters and get as many of them as possible to vote.

This makes sense. Turnout is a function of enthusiasm and suspense; and if suspense seems lacking to many voters, there have been plenty of signs of enthusiasm -- on both sides. The crowds, for example. Mr. Reagan's managers have been careful to screen out from their crowds practically everyone they haven't bused in. But they have had no trouble finding plenty of cheerers. Walter Mondale has been drawing larger and more enthusiastic crowds in the last two weeks than Democratic presidential candidates have for some time. Sophisticates may chuckle at Mr. Mondale's insistence that the enthusiastic crowds are a more reliable forecast of the Election Day outcome than the gloomy polls. But if you assume that one of Mr. Mondale's goals is to stimulate a large turnout for himself and other Democrats, the crowds may be a good indicator. Whatever it was that got these thousands of Democrats cheering may also motivate hundreds of thousands of Democrats to decide to vote today.

There's no way to predict turnout with any certainty, as any reputable pollster will tell you. But the enthusiastic crowds and the positive messages are at least hints that turnout, on one or maybe on both sides, will be up this year. That seems to be the assumption on which the gamblers with something at stake -- the candidates -- based their strategy. And on the success of their urgings hinges, at the very least, the outcome of the dozen or two House and Senate elections -- no one can be sure which ones -- that will be decided today by 1 or 2 percent of the vote.