THE DEMOCRATS badly need a candidate whom people will find credible, one with what the Romans called gravitas -- meaning seriousness, intellectual and moral weight. What they've got instead are candidates with grovel-tas -- by which we mean exactly what you think we do: a pandering refusal to acknowledge that any of the party's constituent groups will have to pay in anything to get the country out of its present fiscal mess.

No one is fooled. Everyone can do the math. The country has been on an eight-year binge of the purest bubbly. The budget deficit, which is the best measure of this, is at a level never before experienced; in certain ways it may be quite literally out of control. The president has spent not only his own share of federal revenues but a sizable percentage of his successor's as well. The cash drawer contains only IOUs.

There will need to be a sizable tax increase in the next administration just to maintain current services. The face-saving trifle in the present deficit reduction plan won't do it. To bring fiscal policy out of the red zone while expanding certain services, as all the Democratic presidential candidates say they would do, there will have to be an even greater tax increase or some offsetting spending cuts.

But the candidates, with the exception of Bruce Babbitt, who is so far last it seems not to matter, won't confront this unpleasant task that lies before them. They've been Mondaled: you say the T-word and you die. They love nothing more than to talk about all the heady, good things they would do as president. They hate to talk about how they would pay for it. Not just hate; they basically refuse.

We print two examples of the High Squirm in which they speak on the opposite page today. Sen. Paul Simon is an advocate not just of increased spending but a balanced-budget amendment to the Constitution. The best this liberal Democrat can come up with as "a possible revenue increaser" -- if that is truly needed, you understand -- is an oil import fee that would mainly benefit the domestic oil industry. Shades of prairie Populism. Gov. Michael Dukakis doesn't like that idea, which would fall hardest on his native New England. His brave proposal is to step up enforcement of existing tax law. And the deadbeats shall lead ye. You remember how Ronald Reagan was going to balance the budget painlessly: he was going to eliminate all that awful waste, fraud and abuse on the spending side. This is the Democratic equivalent, on the tax side.

The Democrats are unmanning themselves on this issue. Worse, by being alternately mousy and dishonest they are reducing their chances both of being elected and of governing effectively if they are elected. If they campaign from a bunker they will govern from a bunker, and that's not what the country needs.