The defendant who acts as his own lawyer has a fool for a client, the old saying goes, but does that apply to politics and Colorado Sen. Gary Hart?

The man who once managed the presidential campaign of former senator George S. McGovern now is running for president, and his blueprint for victory is a reflection of lessons learned in that bittersweet campaign--more bitter than sweet--of a decade ago.

If he is not literally his own campaign manager in his bid for the Democratic presidential nomination, Hart at least has shaped his candidacy with more precision and determination than anyone around him--or, apparently, than any of his op- THE CANDIDATES ponents. Win or lose, the Hart campaign will follow the wisdom of Chairman Gary.

His is a dark-horse candidacy, in the shadow of former vice president Walter F. Mondale and, to a lesser extent, Ohio Sen. John Glenn. Hart is competing for recognition with Sen. Alan Cranston (Calif.), former Florida governor Reubin Askew and others, like Sen. Ernest F. Hollings (S.C.) and Sen. Dale Bumpers (Ark.), who have not announced.

But as one who has been through it, he is neither anxious about his obscurity nor fooled by what lies ahead, and he has been readying himself--and those around him--for a long struggle.

Their plan is a combination of strategically selected opportunities and methodical preparation, and there can be no doubt about who is the architect of all this.

Ten years ago, Hart wrote of the McGovern campaign in his book, "Right From The Start":

"The principle upon which we relied--the principle of a decentralized campaign organization--is one innovation that will have a profound and lasting influence on American politics. Our earliest staff selections were field organizers who lived and worked in the key states . . . . "

Now he is sitting in a Denver restaurant with his campaign manager and political director, describing the keys to his candidacy.

"This campaign will be unique in that it will be highly decentralized," he said. "The individual states will be run by people from those states."

Ten years ago, Hart wrote:

"One of the few serious structural mistakes of the nomination campaign was the decision . . . to separate issue development from the political-organizational backbone of the campaign structure."

Now, he said, "What I've done is put issues first." On this point, he is more than adamant, he is angry.

"I don't like people saying the Democratic presidential candidates are all saying the same thing. We may be, but I am the leader. It's who was first."

Hart said he spent the last two years laying down his "issues base." It culminates in the publication this month of his book, "A New Democracy," which outlines his analysis of the issues that will confront the United States in the future and how to deal with them.

But as described by the general of the McGovern army, the theory of the campaign is that while issues will attract people to a Hart candidacy, only organization can turn that interest into delegates.

There is no magic to Hart's strategy. He has concentrated initially on building organizations in Iowa and New Hampshire, the first two stops on the caucus-primary calendar in 1984, with the hope that he will perform well enough to finish high in the first round.

"It's important for everyone to do well early--especially dark horses," said Joel Bradshaw, a consultant to the campaign.

But Bill Shore, Hart's political director, said there is more to the strategy, and organization, than Iowa and New Hampshire.

"It was a matter of establishing a beachhead while there was still plenty of beach left," he said.

Hart's association with McGovern is likely to hurt him in the Deep South, where there are several primaries and caucuses in mid-March. To offset an anticipated weak showing there, Hart is beginning to devote attention to other states outside the South holding primaries or caucuses in March.

Chief among these are Washington, the first big western state to vote; Oklahoma, with just five fewer delegates than Iowa, and Massachusetts, which could be hospitable because of Hart's liberal ties.

"We're trying to focus on some states where it is less likely that others are concentrating," said Kathy Bushkin, Hart's press secretary.

The goal is to come out of mid-March with enough delegates to keep Hart among the top three candidates.

"The name of this game is delegates," said Harold Himmelman, a Washington lawyer who worked with Hart in the McGovern campaign and is an adviser to the presidential campaign. "The third week of the primary schedule is an important week to show that we can win delegates around the country."

If the nomination isn't locked up by the end of March, Hart intends to be ready to slug it out for delegates in the rest of the states. But he has no illusions that he will have a long list of prominent endorsements even then, nor does he have much hope of the support of organized labor or other constituency groups. In fact, he is trying to foster the impression that he will eschew the traditional constitutency politics but he makes it clear that he welcomes the support of these groups.

He also does not anticipate an embarrassment of riches. As a relative unknown, Hart is having more trouble raising money than either Mondale or Cranston. Like those two, he has qualified for federal matching funds, but has raised less than $500,000 and is behind schedule in his goal of $3 million to 4 million this year.

As a result, Hart will spend a greater share of his time over the next several months raising money in states like New York and California and Illinois. This, in turn, will reduce the amount of time he can spend in Iowa and New Hampshire, two states that require a considerable amount of hands-on campaigning.

Thus, by both conviction and necessity, organization becomes the key--to the attention he has already received for his work in Iowa and New Hampshire, to attracting money in 1983 by demonstrating seriousness of purpose, to spreading the gospel of his "future-oriented" positions on issues, and to capitalizing on whatever opportunities come out of the first month of the caucus-primary season next year.

Hart said he intends to rely on a lean Washington staff and an extensive corps of field organizers and lots of volunteers. He said his campaign will be far less top-heavy than the campaigns of Mondale and Glenn, who already have sizable Washington staffs. At present, Hart has 10 paid staffers in Washington and 18 elsewhere, including eight in Iowa.

Hart's managers say they will run not only a grass-roots campaign, but a bottoms-up campaign as well, an assertion supported by those already working in the states.

"It's very nice compared to other campaigns I've been involved in," said Sue Casey, who is one of two part-time managers in New Hampshire. "They ask you what you want and they deliver it."

Hart's field operatives claim they are making progress although they are having to compete vigorously for organizers, especially with Cranston, who is making headway with the nuclear freeze supporters. In several informal straw polls in off-year caucuses in Iowa, Hart finished a distant second to Mondale, but ahead of Cranston and Glenn.

But asked about reports that Mondale may be better organized in more places than Hart, Shore replied, "I haven't seen evidence of it. I won't dispute it."

In his quest for the nomination, Hart has surrounded himself with an unusual mix of people.

The campaign is to be led by Oliver (Pudge) Hinkel, 46, a Cleveland lawyer and Yale Law School classmate of Hart's, who will be named campaign manager; political director Shore, 28, and press secretary Buskin, 33. Bright and energetic, the three are newcomers to presidential campaign politics.

In the states, however, Hart has recruited several highly experienced organizers. They include Bill Romjue, who ran the Iowa campaign for the Carter-Mondale ticket in 1980 and has been there since August for Hart, and Chris Brown, who organized New Hampshire for Carter in 1976 and 1980 and will oversee operations there, in Washington and elsewhere, for Hart.

There are a number of longtime friends or older advisers of Hart's who will perform a variety of roles. They include Theodore Sorensen, the former aide to President John F. Kennedy, who will be national campaign chairman; Michael Cheroutes, 42, a Denver lawyer who was Sen. Edward M. Kennedy's Colorado chairman in 1980; Mark Hogan, 51, a former Colorado lieutenant governor, and Himmelman, 40.

Hart describes the process of running for the nomination as the theory of concentric circles.

"I am addressing maybe 50,000 people in the country right now," he said. "Beyond that is another circle of maybe 100,000 and then of 1 million and then the country at large." He added, "It's very hard to build a national political base overnight."

No one knows that better than a man who did it once before.