Big gains for Peru's center-left. Social Democrats feel strong after Sunday's vote

It has taken 50 years, but Peru's center-left Social Democrats are finally within shouting distance of the presidency that has so long eluded them. Their candidate, the young and personable Alan Garc'ia P'erez, won 45 percent in Sunday's voting and appears certain to increase that percentage if a runoff vote in June is necessary. It may not be.

Lima's mayor, Alfonso Barrantes Ling'an, who ran second in the field of nine candidates, gave hints Monday morning that he might throw in the towel before then -- allowing Mr. Garc'ia P'erez to be declared president without a runoff.

Mr. Barrantes Ling'an, a Marxist, says he is under pressure from Garc'ia P'erez's supporters and other political groups to do just that. Some of his supporters, however, want him to go into the runoff in hopes that this would strengthen the Marxist cause.

Although the issue of whether there will be a runoff remains unresolved, attention focuses now on what sort of presidency Garc'ia P'erez will run and on his program. As a candidate, he made few promises and kept clear of spelling out his program.

He inherits Peru's worst economic depression in history, with inflation at 130 percent, unemployment and underemployment at 65 percent, and a foreign debt of $13.9 billion.

His Social Democratic party, the American Popular Revolutionary Alliance (APRA), has long championed social and economic reform and been the voice of large segments of Peru's people.

In fact, its beginnings under the late V'ictor Ra'ul Haya de la Torre in the early 1930s centered on calls for social legislation aimed at improving the lot of the masses. APRA has never swayed from that goal.

But with an empty treasury and deep economic problems, Garc'ia P'erez will be hard-put to embrace economic and social reform.

APRA's clarion call for such reform in the 1930s and '40s was so anathema to Peru's economic elite and to the nation's military that APRA was frequently declared illegal. Mr. Haya de la Torre was often in exile or in asylum in a Latin American embassy in Lima. When he narrowly won the presidency in 1962, the military canceled the vote.

Times have changed. APRA no longer sounds so radical. It occupies instead the center of Peru's political spectrum. Moreover, the Peruvian military says it will respect an APRA victory.

In some measure, incumbent President Fernando Bela'unde Terry is as responsible as anyone else for this change in military attitudes. Although his Popular Action party's candidate polled only 3 percent in the voting, he is personally popular and has long worked to keep the military out of politics.

Moreover, the military is preoccupied by a bitter battle with shadowy, leftist rural guerrillas, the Shining Path, who are bent on ``tearing the nation asunder'' as they stated just before the voting, and with a new urban guerrilla group, the Movimiento Revolucionario Tupac Amaru.

The guerrillas failed to disrupt the election, but they still have the potential to do serious harm to the nation.

During the voting, they set off bombs in Huancayo, 180 miles east of Lima, but the long lines at the polling stations all across the country suggested that most Peruvians were simply not intimidated by guerrilla threats to upset the voting.

The army, moreover, reported Sunday that it had picked up several leading guerrilla commanders and raided several guerrilla lairs in the mountains east and south of Lima.

These actions apparently kept the guerrillas off guard and, with the arrests of guerrilla leaders, seriously disrupted their activities.