Troubling ambiguities surrounding the role of Jacobo Timerman in the Senate rejection of Ernest Lefever point up failures of the Carter administration human rights policy that President Reagan wants to scrap.

Lefever's self-inflicted wounds were such that he might have failed confirmation even without Timerman, the exiled Argentinian newspaper editor now living in Israel. But Timerman's dramatic intervention, violating the spirit of Senate Foreign Relations Committee customs, doomed Lefever's hopes to be assistant secretary of state for human rights.

Although there is no evidence that they planned it that way, the senators opposing Lefever used Timerman as a catalyst against both Reagan's human rights policy and Lefever. At no time, however, was there any scrutiny of Timerman's ideological stance as a man of the left or the propriety of his influencing the nomination.

The fact that Timerman was brutalized by an anti-Semitic clique in the Argentinian military transformed him into an authority on proper official U.S. attitudes toward oppression. That mirrors the Carter policy that Reagan seeks to end: equating sporadic villainy inside friendly governments with the organized oppression of the Soviet police state.

Timerman came to intervene in the confirmation fight through the good offices of his American publisher Robert Bernstein of Random House. One of several figures in the literary community opposing Lefever's appointment, Bernstein was scheduled to testify against him before the Foreign Relations Committee. w

Unwritten but unbroken custom prohibits foreign nationsl from testifying before the committee -- certainly never in a confirmation hearing. The breaching of that custom, in spirit if not fact, began when Bernstein asked Sen. Paul Tsongas of Massachusetts, a leader against Lefever, whether there would be room for Timerman to attend the hearing. Tsongs assured the publisher he would find room.

It soon became clear that Timerman would not be just another face in the crowd. When Lefever's fatal inquisition began, one of his chief inquistors -- Sen. Clairborne Pell of Rhode Island, the committee's senior Democrat -- held aloft "Prisoner Without a Name, Cell Without a Number," Timerman's impassioned protrayal of his torture and imprisonment in Argentina.

That night, Timerman dined in Washington with Pell and Tsongas as well as with two anti-Lefever Democrats from the House, Reps. Don Bonker of Washington and Tom Harkin of Iowa. Tsongas told us there was no discussion of using Timerman as a weapon against Lefever but that, as a politician, he immediately perceived the force of his personality.

On the next day, Chairman Charles H. Percy introduced Timerman to standing and thunderous applause. While not permitted to testify, Timerman did better: news interviews spelling out his opposition to Lefever and his preference for Jimmy Carter's human rights policy.

It was better because Timerman was saved from probing questions by unsympathetic senators. La Opinion, the daily newspaper edited by Timerman, was half-owned by David Gravier, an accused international swindler charged with handling ransom money for the Montoneros urban guerriallas. Six men who worked for or with Timerman on La Opinion were deeply involved with the Montoneros.

Those connections certainly do not justify the barbaric treatment meted out to Timerman. But they do uncover a mind set that ignores Soviet and Cuban anti-Semitism while indicting Argentina as today's Nazi Germany. While anit-Semitism is an endemic cancer in Argentina, its government's condemnation of that blight does not suggest the "holocaust" there claimed by Timerman.

The columns of La Opinion under Timerman portrayed Ho Chi Minh. Salvdor Allende and Che Guevara as international heroes. That is no crime, but it shows an orientation with no inclination to assault totalitarianism on the left. At the least, it raises doubts about the qualifications of this foreign national to judge the fitness of a U.S. State Department official.

While Timerman's treatment in Argentina is inexcusable, the merits of his political case are clouded and certainly beyond the competence of U.S. senators to judge. Ronald Reagan believes his government has no business trying to resolve painful internal matters in a troubleed neighbor. The qeustions raised by Timerman's collaboration with U.S. senators in a confirmation proceeding suggest the president is correct