San Salvador, El Salvador — It had all the trappings of a high-school pep rally with a bunch of kids cheerleading the crowds.
Three Mexican-style mariachi bands performed to the wild shouts of the swelling crowds. Vendors hawked mango slices, banana chips, and soft drinks. And everywhere there were blue, white, and red banners.
In another place, the scene could have been a high school basketball game. But here in El Salvador the scene was the campaign finale for Roberto d'Aubuisson, the former Army major whose Alianza Republicana Nacionalista (ARENA , for short) has suddenly become the hottest political force in campaigning before the March 28 balloting for a constituent assembly.
Enthusiasm in the national gymnasium here for d'Aubuisson was evident. When he appeared, and later when he spoke, he was wildly cheered by a crowd that represented in considerable measure what is left of El Salvador's traditional oligarchy and its supporters, who, after three years of civil war, are the country's most endangered species.
The huge gymnasium, which only four days earlier had held a rally for El Salvador's Christian Democrats, led by President Jose Napoleon Duarte, was nearly full - as it had been for the Christian Democratic campaign wrap-up.
But the ARENA rally had more show, more color, more animation. It was obviously well staged. In the hour and a half before d'Aubuisson arrived, the crowd was stirred with political fervor as a mix of music, oratory, and cheerleading kept emotions running high.
And the foreign press was there -- at least 400 strong. There would have been more reporters if a coup had not taken place in neighboring Guatemala earlier in the day; dozens of reporters are on their way there. And there would have been more reporters if President Duarte had not taken a number out into the countryside in a maneuver widely viewed as an effort to undercut the d'Aubuisson rally.
But it was evident that little could undercut the rally. With at least 7,000 people attending, it was a massive show.
It was a massive show of weaponry, too, with guns in evidence at every door and on the platform, particularly after Major d'Aubuisson arrived. A tension was in the air that all the hoopla of the rally could not hide.
Major d'Aubuisson -- whose right-wing rhetoric and strong-willed determination to do away with the leftist guerrillas who have held the country in civil war for three years -- wore a bulletproof vest and was obviously uncomfortable in it.
His bodyguards, several of them burly Salvadorans with rifles and pistols, openly displayed their vests, as they kept wary eyes on the crowd.
Major d'Aubuisson also showed a concern for personal safety, as did his wife at his side. His eyes darted back and forth and took on a most worried look as a bomb went off near the gymnasium. Then, as Army helicpters flew over the scene, he twice turned his eyes toward the domed roof of the gym and wore a worried expression.
But the rally went off without hitches and d'Aubuisson had his final opportunity before the campaign closed to outline his program for El Salvador.
He again promised ''to put an end to this insurrection'' that has engulfed El Salvador in the past three years. ''I can do it in six months,'' he declared.
''That,'' he added, ''will be our first task.''
A chorus of ''tremble, tremble, communists,'' a line from his campaign song, echoed through the high-ceilinged gym.
Along with ending the guerrilla menace, as he termed it, d'Aubuisson also said he will bring ''leading traitors'' to trial. Everyone in the audience knew he meant President Duarte and such top Christian Democrats as Julio Rey Prendes, who like Mr. Duarte, is a former mayor of San Salvador, and currently heads the Christian Democratic ticket for the March 28 vote.
In front of d'Aubuisson was a watermelon -- a fruit that represents his view of President Mr. Duarte -- green on the outside, representing the Christian Democratic colors, and red on the inside, representing d'Aubuisson's view that Duarte is really a communist.
''Christian democracy and communism,'' d'Aubuisson shouted, ''are one and the same thing.''
The former major, who was cashiered from the service in 1979 when the military overthrew its own leader, Gen. Carlos Humberto Romero, also said he will ''restore the military to its rightful position in our nation.''
Most of the ''national program for reconstruction'' that he outlined in his 30-minute address centered on getting rid of the guerrillas, putting Christian Democrats on trial, and boosting police units here.
There was little in his speech on economics or on the social welfare of the 5 million Salvadorans -- the basic problems facing this Massachusetts-size nation.
Mr. d'Aubuisson's supporters expect him to win big thoughout the nation and some opinion polls suggest this could happen. ARENA spokesmen say ARENA is sure to win 40 percent of the seats in the new constituent assembly and - with support from two minor right-wing parties -- to take control not only of the assembly but also of the government.
At least one ARENA spokesman privately worries that if this comes to pass, d'Aubuisson has given very little thought to anything except dealing with guerrillas and building up the Army.
Meanwhile, controversy mounts over d'Aubuisson's role in assassinating Roman Catholic Archbishop Oscar Arnulfo Romero, primate of San Salvador, just two years ago. Documents found in his study at the time of his arrest in 1982 tend to implicate him in the planning. And former US Ambassador to El Salvador Robert E. White has termed him a pathological killer -- an accusation that ARENA spokemen say will soon lead to a libel suit against Mr. White.
None of this came up at the ARENA rally, however, except in comments by preliminary speakers, one of whom charged, ''The world will have to answer to attacks on d'Aubuisson. Our man is here among us as the symbol of what makes this nation great.''
The campaign song of ARENA, moreover, calls for ''sweat and blood'' to be spent by d'Aubuisson supporters. And d'Aubuisson himself told the assembled crowd:
''Our struggle may cost lives. It won't be easy, but it is the only way to do away with our enemies. They must go or we will go.''