The Democratic candidates for president are starting--actually, they started some time ago --on the longest obstacle course in quest of the leadership of a nation since George IV waited 23 years for his father, King George III, to be declared mad. They've read the strategy memos their advisers have written. They know pretty well which primaries and caucuses they will concentrate on, what key issues they will stress, how much money they will raise, when, and from whom. They've even thought about-- though they may not have shared these thoughts with anyone yet--what they will say to the network interviewers on the night of that first breakthrough victory.

What I want to say here is something their campaign strategists probably haven't told them: that there is no perfect campaign strategy. Many of the things they have to do to win the Democratic nomination will work against them in the general election. Many of the things they do in the campaign will work against them if they become president. There is no way to avoid this entirely. But they can avoid some of these problems and at least be prepared to handle the others.

This is more than just a matter of making promises that tie their hands later. I suspect most of them have gulped and decided to promise Iowa caucus voters that they will never, never embargo grain sales to the Russians, even if they invade Western Europe. And I know that most of them have endorsed the United Auto Workers' domestic content legislation, but are squirming in discomfort about that too. If one of them is elected president, he will almost surely rue promises like these. But in a pinch he can break them.

The real dangers to his campaign and his presidency come from the premium the campaign process puts on four different strategies.

1. The premium on stressing today's hot issues. This is a problem that afflicts lesser- known candidates. They need to attract campaign workers and money, and they need to stand out in the crowd. They may believe that they are more competent and able than their opponents, but who's going to take their word for it? They need backers, and a hot issue helps attract them. The problem is that, if the issue suddenly disappears, so does the chance of winning.

Example: George McGovern, running against the Vietnam War. In May 1972, when McGovern trailed Richard Nixon in the Harris poll by only 48 percent to 41 percent, Nixon bombed Haiphong harbor and still met Leonid Brezhnev at the summit. Voters concluded Nixon would bring peace, and the McGovern candidacy fizzled--before the Watergate burglary, before the Eagleton fiasco.

The same thing could happen to a candidate who, like Alan Cranston, stresses the nuclear disarmament issue. If Reagan signs a disarmament treaty with the Russians, what then? Of course, Cranston strategists may decide that without a hot issue his chances are so slim that the risk is justified, and the candidate may believe in it so strongly that he wants to stress it no matter what.

2. The premium on novelty. How does an unknown candidate get voters' attention in early primary and caucus states? By being different. And voters in Iowa and New Hampshire respond favorably. They are acutely aware that their votes are cast at the beginning of the process, and they are willing to take chances on novel candidates they know only a little about. After all, if they make a mistake, it can be corrected by others later. Does anyone really believe that many New Hampshire Democrats, if they thought their decisions would determine the Democratic nomination, would have supported George McGovern or Jimmy Carter, no matter how clean-shaven the McGovern canvassers were or how many houses Carter and his Georgia volunteers made the beds in? These early voters were saying not that these men should be president, but that an early peacenik or a Georgia peanut farmer should be given a chance to prove, elsewhere, that he should be president.

So there is a bias in the process against the front-runner and the familiar and in favor of the unknown and the novel. That gives most candidates an incentive to do offbeat things and advocate offbeat causes. John Anderson's 50-cent gas tax, George McGovern's $1,000-a-year plan, and Ronald Reagan's plan to turn $90 billion of federal programs over to the states--all were intended to (and did) signal voters that these candidates were something different. The problem is that novel ideas often aren't very well thought out and end up causing problems for the candidates later. McGovern is still trying to explain where the $1,000 would come from.

It may make sense for not-very-well-known candidates like Gary Hart and Ernest Hollings to make novel proposals on military and economic policy in order to win attention and votes from those who think things need to be changed drastically. But there's a risk for even well- thought-out novel ideas. Candidates and campaign strategists assume, from what they read in polls and see on the campaign trail, that voters are ready to scrap the system and start all over. Yet when voters are really faced with the choice, what sounded so attractive in New Hampshire in March may be unacceptable in November or in a State of the Union address. Ronald Reagan has found out, the hard way, that there are limits to Americans' desire to cut government, and some programs--like Social Security--they do not want cut at all.

3. The premium on the negative. As the out party, Democrats naturally accentuate the negative. It seemed to work in 1982, and it will come naturally to them in 1984: none of the announced candidates is a member of the House or a governor in a state where Democrats have working control and will be held responsible for outcomes. Their audiences out on the stump and in local Democratic and labor gatherings will cheer lustily every denunciation of Ronald Reagan and all his works. The temptation to rail against the Republicans is well-nigh irresistible.

But it should be resisted. The temptation will be especially strong for those who need to prove their partisan Democratic credentials. John Glenn, for example, has been graded by the media on his success at rousing partisan Democratic audiences in set speeches--although most voters are not so partisan and few of them will listen to a set speech straight through all year. There is a widespread assumption that Democrats won the 1982 elections by strong negative campaigns. There is something to that, but what is startling is not that Democrats won 26 House seats but that, with double-digit unemployment, they didn't win a lot more.

Anyway, the dynamic for 1984 is bound to be different. Voters in 1982 were looking for a mid- course correction of an administration they knew would stay in office. In 1984, they will be deciding who shall govern. They will be interested not just in criticisms of the current president, but in the vision and goals of the Democrat who seeks to be the next one. And they will be leery of any candidate who crosses the line from knocking the incumbent administration to knocking America.

My sense is that underneath voters' negative feelings lies a yearning for a positive vision of the future--one that Ronald Reagan sometimes does a good job of articulating. Voters may be tired of electing presidents who lack the faults of their predecessors but have serious flaws of their own. While on the surface voters may seem negative, deep down they do not want to change in any major way the balance between the public and private sectors or our basic foreign policy stance.

Democrats who accentuate the negative will fail to present an alternative vision and will stimulate fears that they are promising unacceptable change. Even if one of them wins, he will end up as Jimmy Carter did--emphasizing that he does not share the faults of his opponents but unable to articulate convincingly what he and his administration stand for.

4. The premium on interest group politics. If the other pressures work primarily on unknown candidates or those with weak partisan credentials, the premium on interest group politics works on a front-runner like Walter Mondale. When you're ahead, every interest group --from labor to the teachers to the gays-- comes to you and seeks your endorsement of its litmus test issues. If you don't respond positively, the reporters say your campaign is flagging; if you do, they say you're buying off interest groups with goodies like trade restrictions, the separate Department of Education and gay rights. The short-term risk is that the support that is so helpful early in the process proves to be a liability later: winning the AFL-CIO endorsement in December would help Mondale amass delegates in the spring. But will he want to be depicted as the handpicked candidate of the labor bosses in October?

The candidates may be able to avoid the liabilities of interest group politics in the campaign, but they won't be able to avoid them in governing. The idea of giving each organized segment of society its own separate goody turns out to be very costly--and not just because these things cost money. If every interest group is protected against every contingency, then who needs to worry whether the overall economy is productive and growing?

The Social Security increase, instituted by presidential candidates Richard Nixon and Wilbur Mills, says that old people will be protected even when everyone else falls behind. The proliferation of such protections for organized interest groups encourages an "I'm all right, Jack" mentality and goes against the idea, fundamental to the great Democratic successes of the last 50 years, that ultimately we are all in the same boat. It was John Kennedy who said that a rising tide lifts all ships.

Some of the lesser-known candidates have approaches that speak to this. Ernest Hollings' idea of a freeze on spending and taxes has been appropriated, in rhetoric if not in substance, by the Reagan administration. Reubin Askew calls for a national mobilization to make our economy more productive again. Alan Cranston calls for universal national service--a program that suggests that we all have an obligation to society that goes beyond paying those taxes we cannot avoid.

The idea that we are all in the same boat comes more naturally to those candidates who can remember the common effort and sacrifice of World War II than it does for the majority of American adults who know those years only from history books and TV shows. Those candidates have the opportunity to present a vision very different from the Reaganite one, in which America does well by letting rich people get richer, each in his own different and unregulated way. But it is going to be hard to convince voters they can lead them on a common enterprise toward a shared goal, if they are seen spending most of their time promising separate goodies to specific interest groups.

One final word. Every strategy paper the candidates have concentrates on what they must do to win those crucial caucus and primary tests, which are crowded into a few weeks in March 1984. If they are like the major Democratic candidates in 1980, they are not even polling all voters, just Democratic primary participants. My advice to them is this: work backward. Look at the primary season from the point of view of the general election. Look at the general election from the point of view of a president running four years later for reelection. Remember to do what you need to do to make your general election campaign and your presidency a success. This is easier for a long shot like Reubin Askew (who says he is doing exactly this) than it is for a front-runner. But in the long run it makes sense for all of them.

Almost no one will be reminding them of these things in the hectic months ahead. There will be immense short-term pressures at every turn. Yet isn't the job of a president to keep in mind his long-term goals even while coping with short- term pressures? Sure, they can ignore this advice and still win, the opposition can always make mistakes, and, like most politicians, they are optimists. But if one of them wins the wrong way, he is likely to face the fate of most of our recent presidents: rejection and removal. Is that worth all those nights in Holiday Inns?