Even if SALT II is rejected by the Senate, President Carter can still salvage much or most of his strategic arms limitation program. He can avoid the fate of Woodrow Wilson and the rejected League of Nations Treaty.

If, for instance, SALT II fails to muster a two-thirds majority of the Senate, as required for ratifying a treaty, there is nothing to prevent the president from resubmitting it as an executive agreement, which needs only majority approval in the Senate and House.

That, of course, would doubtless inspire howls from the opponents of the pact; but in view of the history of the SALT process, the protesters could hardly claim to be very consistent. Many seem to have forgotten that most of SALT I was presented to the Senate as an interim agreement, which, without objection, was accepted by a vote of 88 to 2.

Actually, the only part of SALT I offered as a treaty (also passed by 88 to 2) was confined to limiting anti-ballistic milliles. SALT II deals with offensive strategic weapons, as did the separate SALT I interim agreement.

At this stage of the debate, it appears the proposed new treaty will win a substantial majority even if it falls short of a two-thirds majority. Should that happen, it is probable that some of the leading senatorial proponents would call on the president to send it back to Capitol Hill as an executive agreement, a form that has been used countless times for other important international pacts.

Although it is possible a majority oppose that option, the president nevertheless would be in a position, as the chief executive, to carry out on his own the terms of the agreement he negotiated with Moscow, assuming that this was agreeable to the Russians.

There already is a precedent for this, since the 1972 SALT I agreement negotiated by President Nixon expired in October 1977. For the last two years, in the absence of a formal pact, the United States and the Soviet Union have simply extended SALT I by informal mutual agreement, while carrying on negotiations for SALT II.

In the event SALT II is rejected, a disastrous breakdown leading to a dangerous and costly arms race could be avoided if Carter and President Brezhnev were to agree on further extension of SALT limitation, thus giving the two superpowers time to resume ngegotiations looking toward Salt III and a more effective reduvtion of arms than SALT II calls for. As a matter of fact, many of the senatorial backers of the treaty now under debate view it only as a step in the right direction, a sort of holding operation until a stronger curb on nuclear weapons can be negotiated.

A new approach to this goal, called a Declaration Policy for SALT III, is being prepared by Sen. George McGovern and several cosponsors. It would recommend and annual 10 percent reduction in the various SALT II limitation categories for offensive strategic arms. The annual reductions would continue for not less than three years, at which time the parties would hold another summit to review the process.

Prof. James MacGregor Burns not long ago quoted Carter as having said that "if Senate approval of SALT II is not forthcoming, he will on his own authority, as chief executive, observe the terms of the agreemtne as long as he is president." As amplified later by the White House, the president would not "escalate the arms race unilaterally in the absence of a treaty, of comparable and verifiable restraint is shown by the Soviet Union."

Arthur Cox, the author of "The Dynamics of Detente," says that "such a course would undoubtedly create a furor, with some senators challenging its constitutionality." He adds, however, that "in view of the public support for SALT manifest in the polls, such action might prove not only to be statesmanlike, but also politically effective."

Sen. Bob Dole of Kansas, a Republican presidential contender, has warned his party that "if the SALT II agreement becomes a partisan issue, Republicans will lose." The party's 1976 vice presidential nominee also said, "Anyone who tries to ride flat-out opposition to SALT to the White House will have the plank pulled out from under them." Even critics of SALT II concede it is more advantageous to the United States than SALT I. So, since the Republicans voted unanimoulsy for Nixon's pact, how can they justify voting against Carter's improved one?

If the Republicans let Carter turn SALT II into a national plebiscite on peace, as they seem bent on doing despite Dole's advice, the president could ride it into reelection.