When news reached here today that Archbishop Miguel Obando y Bravo is to become a cardinal, one of the first to pay respects was the prelate's most powerful adversary, President Daniel Ortega.

The courtesy call at the bishopric by Ortega, who wore the olive uniform of the Sandinista revolution and drove his own black jeep, was a sign of Obando's key political role in this conflict-ridden country even before Rome announced his ascension to the highest rank of the Catholic Church. Observers forecast that with the new mark of respect from Pope John Paul II, Obando's visibility is likely to increase in coming months as Ortega wrestles with the Nicaraguan church hierarchy and its opposition to his Sandinista government.

Obando, archbishop of Managua since 1970, has become a formidable leader of the internal opposition, using as tools against the revolution's Marxist leanings a strong personal popularity and the deep Catholic faith abiding in many Nicaraguans. In the absence of an identifiable opposition political hero, particularly with a censored press, the prelate has assumed a role as the most visible symbol of peaceful resistance for Nicaraguans living here who oppose the Sandinista revolution.

These were the same tools Obando used against the late Anastasio Somoza until the dictator was overthrown by the Sandinistas in 1979. As archbishop, Obando frequently displayed his distaste for Somoza's repression. As a result, when Eden Pastora, as Commander Zero, took over the National Palace in 1978, it was Obando the Sandinista guerrillas called on to mediate with the president.

Obando, 59, was born in the cattle country of Chontales Province. Short and thick, he has the dark skin and directness of Nicaragua's peasant majority.

It was in repeated visits to peasant villages as a younger priest, often riding a mule, that Obando gained his popularity among the country's poor.

But in his 15 years as the capital's church leader, Obando also has gained a reputation for astuteness in his dealings with authority. At a news conference today, for example, he avoided challenging the Sandinistas and expressed hope that his new office will help speed a church-state dialogue undertaken by Ortega earlier this year.

Obando was regarded as one of the revolution's supporters when the Sandinistas first took power. During the guerrillas' final offensive against Somoza, the archbishop had offered an ecclesiastical endorsement of the people's right to rise up against the government. And in the early days of Sandinista rule, he posed no objection to clerics accepting key roles in the government on grounds the country faced an exceptional situation after its debilitating civil war.

Things began to change, however, when Obando concluded that the Sandinistas were setting out to organize a Marxist government instead of the pluralistic democracy he had been pushing for. In addition, the four priests holding office here remained in their positions despite misgivings in the Nicaraguan Bishops Conference and pressure from the Vatican.

Pope John Paul II used his visit here in March 1983 to dramatize papal support for Obando's traditional church hierarchy. The church structure, with Obando at its head, was being criticized by Sandinista officials and sympathetic clerics in what they called the "people's church" as a vessel of traditional bourgeois values and interests of the rich.

But Sandinista demonstrations during the papal visit seemed to reinforce Obando's stand, leaving many Nicaraguans upset at the challenge to church authority and the pope. The Vatican's announcement today appeared to be another gesture to the man who stood beside the pope at that stormy moment.