''JUST once,'' said a voter, ''I would like to be able to vote with enthusiasm for president.'' Last time this voter had cast his ballot like many Americans, for John Anderson - a candidate they liked but knew didn't have a chance of winning.
John Anderson is in the race again. And he undoubtedly will be the recipient of votes from those who are disenchanted with the top two choices.
A lot of Americans won't go to the polls because they are dissatisfied with the candidates. Thus, the declining presidential vote is likely to continue. There is talk of increased registration of blacks reversing this trend. But will the blacks come out in droves to vote if Jesse Jackson is sidelined at the convention? It doesn't seem likely.
The primaries, more than anything, have disclosed this dissatisfaction of voters. Washington Post columnist David Broder calls it a public desire for ''someone else.'' Much of what is going on can be explained by people who are voting against Mondale because they don't like his ties with special interests - particularly now that voters learn more about Hart - because they are concerned that the Colorado senator is, indeed, lacking in experience and substance.
And the fact is the hard core, all-out enthusiastic supporters of Ronald Reagan aren't all that many. Even if the 1980 election is taken as the reference point of Mr. Reagan's popularity, it wasn't - as a useful new book, ''Interpreting Elections,'' by a Princeton political-science professor, Stanley Kelley Jr., reminds us - the landslide that many thought it to be.
Actually, Reagan drew only five-tenths of a percentage more of the total popular vote than did Carter in 1976. (Reagan: 50.9; Carter: 50.4). Professor Kelley also points out in his book that Reagan's share of the total potential vote was 26.6 percent, the third lowest of any winning candidate since 1932.
But within that relatively narrow Reagan popular victory (there was, of course, that impressive electorial-vote Reagan triumph which he and his supporters interpreted as a public mandate), there were millions who were not really voting for Reagan so much as against Carter. That ''against'' vote was pivotal in the Reagan win. The polls at this point show him getting an approval rating well above that vote of four years ago.
But what the polls don't show is how much of this approval is lukewarm. It's among those who are cheering less than wholeheartedly for Reagan that a switch could come in the general election.
At this point the Democrats have not found a candidate who possesses that switch-over allure. Mondale carries too much political baggage. Hart, at first, seemed to have that potential. But the Democratic voters are, on second glance, becoming less than certain that he has all that much of the right stuff.
To many observers the presidency seems ripe for plucking by just the right adversary of Reagan. But he must be someone who would capture the admiration of the independent voters who are looking for a candidate for whom they can cast an enthusiastic vote.
So it is that Hart's job is not just to beat Mondale or Mondale's job just to beat Hart. Each must face up to the problem which that savvy political observer, Bill Brock, expressed in this way: ''What we see in these primaries is a lot of people voting for ''None of the above'' - against whoever is the current favorite.
To defeat Mr. Reagan, the Democratic nominee must stir up widespread excitement over his own candidacy and the prospect of his becoming president.