This is the spring of the Democrats' discontent. Sobered by the specter of becoming a permanent minority party, they are in the midterm throes of trying to formulate a foreign policy that 1) differs from me-too Reaganism and 2) has a fair chance of being a boost rather than a drag at the polls. On the outcome of their effort may hinge the party's national fate -- and much else.

What is striking about this effort is that so many of those engaged in it do not seem confident that Reagan has left them much usable political space of their own. On one side is the president's assertiveness and stated readiness to wield power, which majority-minded Democrats find it safe to snipe at as excessive or crudely applied in some specific cases but which they are not about to denounce as a general rule. That space is already occupied.

On the other side there is a lingering attachment to the particular lesson of Vietnam that teaches a reluctance to get involved even indirectly in a Third World military intervention, of which Nicaragua is now the most painful case. Critics call this the Vietnam syndrome or "neo-isolationism." There is political space here, but only a minority of Democrats appears prepared to occupy it.

On defense, as distinguished from foreign policy, the Democrats have already achieved a consensus considerably tighter than the Weinberger-to-Grassley spread evident among Republicans. Budget pressures have helped the party's liberal cost cutters and conservative defense experts find common ground.

Foreign policy, however, is the turf where the hard collisions of values take place. The Democrats have made several runs at finding a habitable middle. The party set up a task force recently under Rep. Stephen Solarz (D-N.Y.), a liberal who wants the Democrats to pursue power as well as principle. An early draft of his report aimed at consensus, but, on the litmus Nicaragua issue and elsewhere, it produced argument on familiar lines and is now back in the shop for repairs.

The Democrats' conservative wing had its own moment the other evening. It happened at a dinner of the hopefully named Coalition for a Democratic Majority, a minority faction whose hero is the late senator Henry Jackson.

Rep. Claude Pepper (D-Fla.), 85, got through a rousing tribute to the old Democratic anticommunist internationalism without so much as a single allusion to the disaster that overtook this policy in Vietnam.

Former Virginia governor Charles Robb, 46, then went to the heart of the Democrats' current dilemma by presenting himself as son-in-law of a man (President Lyndon B. Johnson) "whose agony about Vietnam was greater than most people realize" and as representative of "a new generation of Democrats whose political views were shaped by the social movements of the 1960s, the rampant inflation and pessimism of the 1970s and the Vietnam War."

Robb worked his way through a routine critique of Republican foreign policy ("no clear moral alternative to the cynical power politics of the Soviet Union") and then tackled his true target, the party's "isolationist" stream. The positioning was deft: "a foreign policy which neither renounces nor relies exclusively on the use of force, a policy tempered but not paralyzed by the lessons of Vietnam." But by the hard part he had succumbed to the new Democratic syndrome of wanting to have it both ways.

Saying he was offering a two-track policy (negotiations with the Sandinistas, support for the resistance), he actually offered a three-track policy whose third track -- reform of the contras by putting conditions on aid -- can only have the practical effect, if it's serious, of undercutting the first two tracks. Swing Democrats are going that way these days, including such CDM stalwarts as Sen. Sam Nunn (D-Ga.) and Reps. Les Aspin (D-Wis.) and Dave McCurdy (D-Okla.).

But it's too slick. If reform of the contras were easy, it would have been done already. If reform is hard -- and it is -- it will get in the way of aid. I would take a more direct approach: If you think there is no other way to serve American interests, grit your teeth and vote for the aid: this is Reaganism. If you think that the contras' shortcomings, the burden of past American interventions and the lay of the Latin American land make aid unwise, and that an adequate security fence can be erected around Nicaragua anyway, then vote against aid. The Democrats keep saying they need a consensus. Maybe they do for reasons of their own. But the country needs a good policy.