FROM WHAT ONE READS these days about ratification of the proposed constitutional amendment to give the District of Columbia voting representation in Congress, one might think the Republican Party is the great opponent. But had it not been for GOP support in Congress, the amendment would not have gone to the state legislatures in the first place. Great credit for mustering that support goes to Paul Hays, chairman of the D.C. Republican Party, and to Bill Brock, chairman of the Republican National Committee. Understandably, both chairmen have been disappointed by the thin initial support that GOP state legislators have given to ratification. But they continue to believe that, once their colleagues in the state capitals have a full opportunity to consider the merits of the proposal, they will see the moral rightness of the amendment, not to mention some long-range practical benefits for their party.

That is why formal leadership of the national ratification effort must be shared equally between prominent members of both major parties. Mr. Brock, who is rightly credited by his party colleagues for helping to produce a new wave of Republicans in the state legislatures last month, certainly recognizes the importance of Republican participation in ratification and already has been working for it around the country. He also has written a "Dear Fellow Republicans" letter, which is featured along with other GOP endorsements of the D.C. amendment in an advertisement in the Ripon Forum magazine being sent to party members and state legislators. In it, Mr. Brock notes that the 1976 Republican National Party Platform called for full D.C. representation, and he urges Republicans everywhere "to assist in implementing this plank." Other supporters quoted include Sens. Strom Thurmond of South Carolina, Barry Goldwater of Arizona and Charles Mathias of Maryland, and Reps. Robert McClory of Illinois, John Buchanan of Alabama and Stewart McKinney of Connecticut.

While all of these legislators cite sound arguments that rise above partisan interests, they are well aware of the misconceptions and political fears that give some of their party colleagues pause about D.C. representation. Most obvious is the GOP concern about the probability of adding two more Democrats to the Senate. But thoughtful Republicans, besides pointing to the justice of representation, argue that their party's chances of cracking the present Democratic lock in the District would be enhanced by contests for the House and Senate that would attract top-flight talent to run under the Republican label. Besides, they argue, sooner or later District voters will reject one-party domination.

As Delegate Walter Fauntroy has said to columnist William Raspberry, "broad-based support and carefully researched strategy" are critical, which means a bipartisan, biracial leadership equipped with the necessary information. This effort, to be successful, cannot be rushed; the ground in each state must be well prepared. And the struggle, as it unfolds, cannot be masterminded -- or led -- by any single figure.It is going to have to be a bipartisan, collective enterprise.