AS THE unemployment rate topped 10 percent, Democrats were having great fun lambasting Reaganomics. But there is not much evidence yet that they are running away with the election, and one reason is that voters are not sure of the answer to the question Reagan Republicans put: what's your alternative? However disappointing the results of its economic policies may be, the administration still has a lot of running room. There has been no clearly articulated policy from any other quarter.

It would be unfair to denounce the Democrats for defaulting on their responsibility to present an alternative: opposition parties typically have difficulty framing a clear economic policy. House Democrats actually did come up with a detailed counter- budget in 1981, though they were unable to muster enough votes to pass it. But the Democratic budget differed from the Reagan budget only at the margins: it cut taxes somewhat less, cut domestic spending somewhat less, increased defense spending somewhat less. It did the things the Reaganites wanted to do, but more cautiously.

This is what most Democrats on the campaign trail seem to be advocating this year. You will hear some call for massive public jobs programs, but most Democrats urge such nonrevolutionary steps as scaling down the third year of the Reagan tax cut and holding down defense increases a bit. It's hard to conclude that such policies, if they had been followed in 1981 and 1982, would have produced an economy without some rise in unemployment. The most effective practitioners to date of such policies are not Democrats, but the Senate Republicans -- Sens. Baker, Dole, Domenici -- who crafted this year's budget and tax bills.

The Democrats' failure to suggest an attractive alternative to the administration's unattractive policies is not accidental. Our economic difficulties are different from other post-1945 troubles: some leading industries seem to be permanently contracting, and the tools that used to ease inflation and unemployment are not working as they once did. No one has a formula to produce the kind of economy almost everyone wants. That is the Republicans' trump card in the 1982 elections. The Democrats can summon up moral indignation over 10.1 percent unemployment, but neither they nor, so far as we can see, anyone else can summon up a plausible solution for the problems that ail us.