:THE CAMPAIGN FOR ratification of the D.C. congressional representation amendment starts its second year today. The first was not encouraging. Six states -- New Jersey, Michigan, Ohio, Minnesota, Massachusetts and Connecticut -- have approved the proposed constitutional change. But haste and tactical disarray caused embarrassing setbacks in several others, including that narrow, unnecessary defeat in the Maryland House of Delegates. Worse, while opponents of the amendment were getting organized, the bipartisan coalition that had shepherded the measure through Congress fell into discord and squabbling and has so far been unable to regroup.

But none of this has in any way diminished the case for granting District residents voting representation in the Senate and House. On the contrary, those citizens have now gone through one more year of being subject to federal taxes and other laws -- just like all other Americans -- but, unlike all others, lacking any voice or vote in the levying of those taxes or the making of those laws. This situation is fundamentally unfair. Even many of the amendment's opponents recognize that, while questioning whether D.C. representation is the proper remedy for that wrong.

By now, proponents of the amendment have been through all the arguments so often that they can probably recite the answers in their sleep. The crucial point, which the last year's setbacks underlined, is that state legislators and voters elsewhere are not nearly as familiar with the issue, and much more susceptible to opponents' arguments, including some that are grossly misleading or plain wrong. What is sorely needed is a patient, temperate, state-by-state educational campaign. And that gets back to the problems of leadership and organization that have hamstrung the amendment drive so far.

Right now there is a weary stalemate between the voting rights corporation set up last spring by Del. Walter Fauntroy, Mayor Marion Barry and Council Chairman Arrington Dixon, and the coalition of local and national groups that was so effective in the congressional fight. The two groups' inability to settle or set aside their differences has delayed fund-raising and retarded efforts to prepare for forthcoming tests in California and other states.

Surely there's a logical way to allocate the work. Mayor Barry, for instance, is in a good position to mobilize local enterprises and the growing number of national businesses and groups that have offices and investments here. The national organizations with affiliates and lobbying experience in various states should certainly be encouraged to use those assets. And all of the local leaders involved must be able to acknowledge by now that some of their own ambitions and enthusiasms need to be restrained in the interests of building a nationwide base of support for the amendment and demonstrating that, as a matter of basic justice, it has substantial backing among people who are not urban, Eastern, liberal and so on. It also would help greatly if, as attorney Joseph Rauh suggested in an op-ed piece yesterday, all politicians -- starting with President Carter -- would refrain from attacking "Washington" as a bastion of misused power and influence. The maendment is concerned with extending basic rights to ordinary citizens who have no power to elect any representatives, and no influence over the Congress that assembles here. There are still six years in which to get that message across.