This is the winter of the Democrats' discontent. Since last November the party has been wringing its collective hands over Ronald Reagan's political ascendancy. It flagellated itself on TV the night of the State of the Union message. At its latest conclave, it brought in David Gergen to tell it the secret of Ronald Reagan's success and a "motivational" psychologist from Elizabeth Arden cosmetics to diagnose its ills. Hardly a week goes by without some leading Democrat's issuing a call for the party to come up with new ideas and values, or to return to some of the old ones.

Meanwhile, with a few notable exceptions, the party's leaders have tried to keep up with the president in running as far and as fast as possible from the central domestic issue of our time -- the serious and lasting damage of the administration's massive budget deficits. Because of those deficits, we are busily distributing all over the world IOUs that our children will have to honor. And once foreigners begin to find our mounting pile of IOUs less attractive, as inevitably will happen some day, financing the deficits will start soaking up the nation's limited supply of domestic saving and thereby squeeze out the productive investment on which our future living standards depend.

Given their huge magnitude, there is no way to cut the deficits down to size without attacking all the main components of the budget -- reducing defense spending, raising taxes, imposing a temporary freeze on cost-of-living adjustments in Social Security and paring other forms of domestic spending. That fact is an open secret. Nearly everyone who knows the budget numbers is aware of it -- David Stockman, Alice Rivlin, Martin Feldstein and Walter Heller, to name the most prominent. But the Democratic leaders appear to have joined a conspiracy with the administration to keep silent about these facts.

The president pays lip service to cutting the deficit and says it all can be done by reducing civilian spending, while defense and Social Security outlays go scot-free and taxes remain untouched. The Democrats pay equal lip service to deficit reduction, but try to distinguish themselves by concentrating on cuts in defense spending. While some cuts in the defense budget are in order, they know and I know that a $250 billion deficit can never be cured principally by cutting the Pentagon's budget. Raise taxes? Why, the Democratic leadership would rather be caught dead than espouse a tax increase, especially after what happened to poor Walter Mondale. Freeze cost-of-living allowances in Social Security? Even more unmentionable. They would much rather play a coy waiting game, lie back and -- they hope -- let Ronald Reagan rhe whirlwind of his own policies. All the political conferences and idea seminars in the world can't make that strategy add up to anything but an abdication of leadership.

The Democrats, I think, badly misread the current situation in two ways. In the first place, you cannot explain Ronald Reagan's political strength purely on the basis of personal magnetism and great PR. While the president does derive some of his political strength from being the Great Communicator, he also gets it by possessing a stubborn core of ideas and principles that he sticks to even when short-term political considerations argue for their abandonment. (Balanced budgets, it turns out, are not in that core of ideas, but an unshakable belief in the virtues of low taxes and a massive defense buildup is.) He trims and cuts like all successful politicians, but he doesn't yield on those core ideas. And so, beneath the tactical maneuvering of a shrewd politician, voters also sense some fixed principles and a willingness to take political risks to carry out those principles. People like that firmness, even when they are not sure they fully subscribe to all the principles involved.

The second fallacy of current Democratic strategy is the belief that if they only play it safe, Ronald Reagan's budget deficits will finally do him in. They will then inherit the mantle. But the terrible fact about the deficits is that we may be able to keep on issuing the IOUs to ourselves and the rest of the world for some time yet. With a little bit of Irish luck most of the long- term damage from the budget deficits may not show up for a while, maybe even for four years.

On these matters of timing, of course, no one can be certain. The Democrats can play it safe and gamble that the toss of the economic coin will give them power in 1988. But if they lose the toss, they will have neither power nor a basis for principled opposition. And even if they win, the power won't last very long because they will not have laid the necessary groundwork to do the very hard things that will then be necessary to undo the legacy of Reaganomics. Or, they can take some risks now and tell it like it is -- tax increases, Social Security freezes and all.

You simply cannot make it credible to the public that the administration's deficits are a massive national problem unless you also show a willingness to propose effective remedies against it. While no one can guarantee success by that route either, the Democrats will at least have made themselves a party able to govern when they do come to power. In politics, as in business, there are few large returns without large risks.

It is hard to know exactly where to draw the line between making pragmatic accommodations and taking the strategic risks that go with leadership. I don't pretend to know just where that line is. But right now it is my impression that most of the Democratic leaders are so far behind that line that they risk being lost from sight.