AT FIRST, WE THOUGHT maybe some greenhorn headline writer had muffed, or that the ghastly heat had finally gotten to one of the senior senators from the Old South. Could it really be that Sen. Strom Thurmond (R.S.C.) supports the proposed constitutional amendment to give the District full voting representation in Congress? It could indeed - and there's good reason behind his position on the matter. Not only does Sen. Thurmond correctly recognize that this is a civil-rights and human-rights issue, but he is acutely aware that significant numbers of his constituents are telling him they favor the proposal.

In fact, if the propsal does win the necessary support of at least two-thirds of the Senate, it will be due in no small part to the very same factor that ensured its burial in the past - namely, that the issue is of special interest to all black Americans. That alone was enough to prompt Southern opposition in previous years. But today, it's just the other way around: The black votes is important to candidates; for example, blacks make up more than one-fourth of the registered voters in South Carolina, where Sen. Thurmond is up for re-election this fall. And so far many a congressional candidate, a vote to do right by the District is now a "plus" back home.

And well it should be, for far broader reasons that involve all Americans - reasons that have to do with, among other things, taxation without representation. Thus, the vote in Congress should not divide along partisan or "liberal" or "conservative" lines. Moreover, as Sen. Thurmond says, giving District residents votes in Congress is important "to set an example for the rest of the world" and failure to do so "could result in the issue being thrown back in our faces at a time in history when the United States is urging other nations to extend full human rights to their own citizens."

Perhaps that's why more than two-thirds of the House of Representatives voted for the amendment this year, and why increasing numbers of people in the 50 states supported a nationwide effort on behalf of the proposal. Now it is up to the bipartisan Senate leadership to react accordingly and schedule the vote as soon as possible.*