From El Salvador to Europe and the Middle East, the Reagan administration is bumping up against the limits of superpower influence. Most administrations have come to power thinking that they can accomplish more in foreign policy than the realities of competing nationalisms will permit. But Reagan administration officials, more than most, came in stressing that a buildup in military power could help shape political perceptions around the world. There is some truth in this concept over the long run, but so far it has produced few results for this administration.
The perception is fast growing in Washington, if not elsewhere in the world, that more than halfway through his first term, President Reagan has no major foreign policy victories to his credit. A ''win'' on at least one front is badly needed if he is to run, as seems likely, for reelection.
Liberals are beginning to point to what they consider major Carter administration achievements - the SALT II treaty, the Panama Canal treaties, the Camp David accords, and the normalization of relations with China - as the type of thing that seems beyond the reach of the Reagan administration.
The administration is having to face up to the fact that in Central America and the Middle East it faces a long, hard struggle to establish stability and bring about a peace that is to its liking. There are numerous signs, meanwhile, that the administration may be moving in a more pragmatic fashion to accommodate its policies to unpleasant realities on the ground in both of these troubled regions.
The administration is also being forced increasingly to take into account the views of its allies and public opinion trends both here and in Europe. The administration's pragmatism is evident in its toning down of the conflict with West European allies over East-West trade.
Although President Reagan's instinct has been to try to deprive the Soviets of Western technology, he has decided to play down allied differences for the moment in the interest of holding a harmonious Western economic summit at Williamsburg, Va., next month. As the London Economist puts it: ''There is no shortage of disputes, but the understanding seems to have sunk in that the Western alliance cannot afford open new battles on top of the drama over the deployment of American nuclear missiles in Europe.''
Nothing that the administration proposes is any longer automatically accepted by NATO, and that has been the case for many years now. The same applies to Latin America, where the US once was able to dictate its will to some nations. Partly because of their anxiety about American policies in Central America, Colombia, Mexico, Panama, and Venezuela have been pursuing their own peace plan. Mexico recently rebuked the United States in a statement issued from the conference of nonaligned nations, arguing against what it described as a ''simplistic perspective'' on international realities.
The consolation prize for the administration in all this seems to be the limits on the other superpower, the Soviet Union. Even while building their military strength at a steady rate, the Soviets have not always been able to impose their will on other nations - even including those nations on the Soviet borders. The continuing strong Afghan resistance to the Soviet occupation of Afghanistan is one example.
Then there is the constant impulse within Eastern Europe to loosen ties with the Soviets. The Soviet economic model, whose failings are now obvious to all, fails to inspire. In the third world, any number of nations have turned quietly to the US for investment and economic cooperation, having failed to see any economic payoff from close relations with the Soviet Union. The small West African nation of Guinea, which ended up getting Soviet tractors more suited to Siberia than to the African heat, is a prime example.
Given the limits on Soviet power, some experts argue that this is a time of unprecedented opportunity for American diplomacy. Former Secretary of State Henry A. Kissinger asserts in an interview in the latest issue of Parade magazine, for example, that the US now has a ''historic opportunity for a major negotiation with the Soviet Union.''
In the Parade interview, Dr. Kissinger contends that the Soviets might be propelled into negotiating by factors including ''instability of leadership; instability of the economy; major problems in the whole structure of society, such as the emergence of a non-Russian majority in the population; major problems in the satellite orbit; a need, sooner or later, to tackle domestic reform.
''Just as we have been driven to a recognition of the limits of what we can do, so the Soviets are bound to be driven by a sense of the deadlock inherent in a policy of pressure - especially if we are wise,'' said Kissinger.
The Reagan administration has clearly not gone as far as Kissinger would like it to go in negotiating with the Soviets over arms control, restraint in international conduct, and the future of East-West trade. But it has shown some small signs of trying to improve the atmosphere in relations with the Soviets: It has offered Moscow a long-term grain sales agreement; softened its opposition to the Soviet-European gas pipeline; decided not to accuse the Soviets of SALT II treaty violations until it can study the matter further; given up explicitly linking arms negotiations with Soviet international behavior; and participated in NATO studies that could result in the removal of some tactical nuclear weapons from Western Europe.
There is one limitation on American power, however, that does not exist in the Soviet Union and that is the power of Congress. If the Soviets think that Congress will limit the administration's power to intervene in key areas of conflict, they might be inclined to wait out this administration. This might be even more the case should the Soviets calculate that the Democrats have a chance to regain the White House in 1984.
The administration appears to have gone a long way to accommodate congressional concerns over El Salvador. To obtain additional aid, it has agreed to several demands from a key congressional subcommittee chairman, Rep. Clarence D. Long (D) of Maryland. In response to Representative Long's suggestion, President Reagan is expected to appoint a special envoy to help arrange elections in El Salvador that would theoretically be open to all political factions, including the left.
One of Long's aides said the congressman sees this as a sign of administration pragmatism. But the aide also said that Long is not sure how much of the administration's compromise is ''show'' and how much is ''real.'' The skeptical Long is, therefore, expected to propose that his subcommittee approve half of the $60 million in ''reprogrammed'' aid that the administration is requesting for El Salvador and hold back on the rest until it sees results in the way of elections and improvements in the performance of the US-backed Salvadorean Army.