It was almost a throwaway line in the congressional testimony of Thomas Enders, assistant secretary of state for inter-American affairs. He was doggedly defending the administration's "certification of progress" on human rights by the government of El Salvador, a condition imposed by Congress for continuing American aid.

The Reagan administration bitterly opposed this congressional assumption of presidential prerogatives when it was enacted two years ago. But there was Enders strongly implying that the administration will offer no objection when the law comes up for renewal this year. Now, you can put part of this down to the making of a virtue out of necessity, and part to the looseness of the law. "Certification" every 180 days has become routine. Yet only in terms of the volume of human-rights violations, as distinct from their nature, could it be argued that El Salvador has made "progress."

Still, the way Enders put it was significant: "The leverage (on the Salvadoran government) under certification has been helpful--indeed, perhaps essential."

Essential? Is that to say that the administration's devotion to human rights and/or its influence in San Salvador is so feeble that congressional reinforcement is a necessity? That may not be quite the cry for help ("Stop me before I kill someone") of the compulsive psychopath. But surely it is the beginning of a whimper in an administration policy that began two years ago with such a bang, with Alexander Haig drawing his famous line in the dust, hurling the gauntlet at the Cubans and the Soviets, declaring Cold War.

In those days we were told not to worry about the government's repressive ways, the "death squads," the awful carnage unrelated to conventional military operations. The United States would give the government the military tools and the training for successful "search and destroy" counter-insurgency operations; democracy was just around the corner.

But now look: the rebels are running those U.S.-trained "quick reaction" forces ragged. Enders himself publicly concedes a "standoff." The hit squads take their weekly toll. Only the promise of elections next year gives any meaning to the fragile democratic process so loudly hailed when the hard right won last year's preliminary voting for a constituent assembly.

Enders' air of resignation to a measure of congressional oversight is not the only sign that at least some elements in the policy-making apparatus have a sense of sinking in the El Salvador quagmire. A heavy debate is shaping up within the administration over how to wriggle free.

You get some sense of this in the vehemence of the denials of any policy change. When it was reported recently that Enders had secretly endorsed a new split-level approach (continuing support for what passes for a central government, while discreetly exploring a negotiated resolution of the conflict), America's "Iron Lady," U.N. Ambassador Jeane Kirkpatrick, way oversimplified what Enders is actually up to.

She sought to reject any such notion in the name of "Washington, and the State Department, the White House and the U.S. government." It was classic overkill, a ringing denial of any intent to cut a deal with one or another of the various opposition factions by way of divvying up power without benefit of democratic process.

Enders has said as much publicly. What he has laid out in a memo to Secretary of State George Shultz is much more of a presentation of alternative ways to arrange a solution through diplomacy than a hard-and-fast recommendation. He is reportedly looking for some way to broaden the peacemaking effort, avoiding direct U.S. dealings with the rebels while searching for a solution in a wider Central American context.

He would like to energize a concerted effort by the countries in the area with the most to gain by defusing the East- West aspect of the conflict. The ideal objective would be the removal of all outside involvement in the internal clashes--American as well as Soviet and Cuban. Some kind of multinational forces and institutions would be mobilized to make and keep the peace.

That's a tall order, and also a measure of how dismal the prospects look, given the way things are proceeding in El Salvador, Nicaragua, Guatemala and the rest of the neighborhood. Congress is increasingly restive. Scorn for the "certification" ritual for El Salvador spares talk of cutting the present military-aid level even as the administration talks about the possible need to quadruple it if today's "standoff" is not to slip back into almost total anarchy.

Small wonder that Tom Enders should be almost welcoming congressional constraints in the interest of strengthening the administration's hand--or that the realists at State, at any rate, are beginning a search for alternative approaches to the problem of El Salvador.