Sen. Gary Hart, the early front-runner for the Democratic presidential nomination, is doing something unusual. He is running for the White House, not by sewing up commitments or signing up consultants, but by seeding the political landscape with ideas.
The Coloradan, who is retiring from the Senate this year, ran as the ''new ideas'' candidate in 1984, when he had little to lose by the gamble. This time, the polls put him far enough ahead of the field that he might easily choose a more conventional strategy. But rather than resting on the credentials he gained from his almost-successful challenge to Walter Mondale, Hart is taking the risk of defining views publicly and prodding other Democrats to join in the dialogue.
However it works out for him, that kind of gutsiness deserves applause.
Last week, Hart laid out the broad principles of a foreign policy of ''enlightened engagement,'' and some of its specific applications, in three speeches at Georgetown University. A few weeks back, he published a book on military strategy and Pentagon management called ''America Can Win.'' Earlier this year and in 1985, he introduced legislation and gave major speeches on trade and monetary policy, education, job-training and economic development.
His work has an intellectual coherence that goes well beyond the level of the average stump speech. The foreign-policy lectures hang on the assumption that ''the diffusion of power'' to Europe, Japan and the Third World countries necessitates a new look at the Soviet-American contest. That thesis can be debated by those who still see a bipolar world.
Even more challenging are some of Hart's specific proposals. He argues that U.S. banks may be required to write down some of their loans to debt-ridden Third World countries. He advocates pressuring the South Korean government to permit open political opposition. He says it is time to raise the issue of redistributing the NATO defense responsibilities in Western Europe.
If he is in tune with the majority of his party in opposing aid to the anti-Sandinista contras in Nicaragua, he is surely cutting against the grain in condemning much Democratic-sponsored trade legislation as backward-looking protectionism, a new form of isolationism.
Whether Hart is right or wrong in all his views, he is genuinely trying to start a Democratic debate. He is not alone in this enterprise. New York Gov. Mario Cuomo has given some notable speeches in the past 15 months and former Virginia governor Charles Robb is also trying to define a program and philosophy for his party.
But Hart's effort has special significance. Cuomo is still shy about expressing presidential ambitions, and Robb is the darkest of dark horses. Hart is a full-blown, front-running presidential contender. When he talks policy in substantive terms, he tugs the others into competing in the arena of ideas.
In an interview last week, he said, ''1987 has to be the issues year for Democrats, and I'm going to try to make it that.''
The cynical view of Hart's effort is that he is simply trying to immunize himself against a 1988 repetition of Mondale's famous put-down question: ''Where's the beef?''
I think that is a misreading of his motive. Hart understands that in the heat of the 1984 primaries, ''Mondale was not challenging my substantive ideas, he was questioning my character.'' Asking ''Where's the beef?'' was just a semipolite way of getting Democrats to ask themselves, ''Who is this guy Hart? What do you really know about him?''
That is a question Hart still has to answer -- by opening more than his mind to the voters and by demonstrating that he has leadership credibility with other politicians.
But credit Hart with at least one important insight, all too rare among Democrats in 1986: ''Ronald Reagan won the presidency because of ideas -- not charm.''
''Ideas have power,'' Hart remarked, ''particularly in a time of great change like this one, when people are looking for ways to understand the transition in their lives.'' He is convinced that the only way Democrats can win a national election again is ''if we talk up to people, not down.'' And that means organizing a serious policy debate before the political dialogue is reduced to 30-second TV spots and 90-second ''sound bites'' on the evening news, as will happen once the accelerated calendar of 1988 primaries takes over.
Hart will do his part to push the policy debate to the forefront in the next 18 months, but even as front-runner, he cannot do it alone. The Democratic Party has ducked the issues debate for the past 18 months, fearing more wrangles would hurt its chances in the November elections. But it cannot duck them forever.
A series of 1987 party-sponsored policy forums involving the presidential hopefuls and other Democratic leaders would be a real contribution to testing the direction the nation wants to go in the post-Reagan era.