There is a looming presence behind this Sunday's election in El Salvador: the military. In governing this country, the armed forces are as important as the President , if not more so. And whoever moves into the presidential palace here will have to contend with a military that has paid little heed to civilian politicians over the past 50 years.
Military leaders say they are neutral in the current elections and that they support the democratic process. But the reality of El Salvador's political landscape belies this.
Some Army commanders administer their regions like fiefdoms, reducing civilian leaders to figureheads. Some quash even mild social dissent through intimidation, and are widely believed to be responsible for the disappearances and murders of local townspeople.
If Christian Democratic candidate Jose Napoleon Duarte is elected president, as most observers expect, he is likely to face a political confrontation that few here feel he can win. Mr. Duarte, considered a moderate, has often been a critic of military intervention in this country's fragile political process.
Hence, says Rene Fortin Magana, a close friend of Duarte and former presidential candidate of the small, liberal Democratic Action Party, the private sector and military may ''boycott'' a Duarte government.
This, he adds, would cause political havoc.
In response to such considerations, Duarte is expected to soft-pedal any reforms.
If elected, his close advisers say, he probably would not enter into serious negotiations with the rebel forces. Military leaders have long contended that negotiations with the leftist insurgents are unacceptable.
However, Christian Democratic Party officials say a Duarte administration would move to purge members of the rightist ARENA (National Democratic Alliance) party from top spots in the agencies that control the nation's agrarian reform program.
ARENA's presidential candidate, Roberto d'Aubuisson, appears to be running well behind Mr. Duarte. Considered an ultra-rightist, Mr. d'Aubuisson is a former Army major who once headed the National Guard's intelligence section. He has been accused of involvement with death squads and has opposed the moderate social reforms supported by the Christian Democrats.
If Mr. d'Aubuisson wins the election, the influence of the military probably will not be challenged, well informed observers here say, although there may be some power struggles unrelated to political ideology.
For all the talk of an ''emergent'' democracy, El Salvador is a country that is still ruled by a state-of-siege law that suspends freedom of movement, the inviolability of communications, and the freedom of assembly.
Public employee unions are illegal. Strikes are considered a ''subversive'' activity, and are outlawed under a decree promulgated in December 1980.
Public utilities (telephone, power, water, and railroads) are militarized. All public utility employees are under direct control of the Ministry of Interior, and unions for these workers are prohibited.
Wages have been frozen since Dec. 12, 1980, although the prices of basic commodities have doubled and tripled. Collective bargaining is illegal.
Anyone picked up by the state security forces or the military can be held for six months without charge or access to defense counsel. Detention can be extended by a military judge for an additional six months.
Two newspapers, La Cronica del Pueblo and El Independiente, and the printing press at the Catholic University have been shut down since 1980. The one newspaper, El Mundo, that struggles to maintain a semblance of objectivity is forced to practice heavy self-censorship because of frequent death threats against its editors and staff.
The Army effectively controls Salvadorean society through such measures. Its high command has reportedly drafted a letter to the soon-to-be-elected president , advising him to stay out of military affairs.
Under the Salvadorean Constitution, the President is commander in chief of the armed forces. And Mr. Duarte publicly downplays the military's influence on government.
''The military will support democracy,'' he says, ''and it will accept the basic rules of democracy. When I become president I will also become the head of the Army.''
But advisers close to Duarte privately worry that he will be severely restricted by the armed forces. Nor have Duarte's past experiences with the armed forces left many people here with much confidence in his ability to hold the institution in check.
Duarte's tenure in the second and third juntas from January 1980 to March 1982 saw the worst period of political violence in Salvadorean history, with the possible exception of the 1932 abortive uprising. More than 25,000 people were killed, most by government security forces, according to the research department at the Central American University in San Salvador.
Duarte contends that although the number of killings was high, his first government slowed down the acceleration in the pace of violence:
''When I took power there were 3,000 killings a month. When I left, the killings had dropped to 500 a month. So killings diminished. I will now further reduce the causes of violence, especially since I will have more than I did before. Before we were part of a government, now we will be the government.''
Mr. Duarte's supporters, however, fear the ultra-right and its allies in the military may attempt to destabilize the new government with increased political violence.
''It seems evident to me that Duarte will win,'' says Mr. Fortin of the Democratic Action Party, ''but it also seems evident that the opposition will attempt to destabilize him (Duarte) through increased violence. It will be a triumph for him to remain in power.''
Some observers here speculate that Duarte will appoint Gen. Jaime Abdul Gutierrez, one of the leaders of the 1979 reformist military coup, to a high military post.
Duarte, these observers suspect, will attempt to retire the chief of the Air Force, Col. Juan Rafael Bustillo, and the director of the Treasury Police, Col. Nicolas Carranza. Both men are considered ultra-rightists with alleged links to death squad activity.
But, these observers contend, Mr. Duarte is very unlikely to attempt to alter the basic structure of this country's armed forces.