Few people claim ever to have seen him crack a smile, fewer still are said to be his close friends or confidants, and he has given one press conference in six years.

He has twice been elected president of Portugal by large majorities, supported by a wide spectrum of ideologically diverse parties, yet most of the political leaders openly dislike him, and he them. He has no political party of his own.

President Antonio Ramalho Eanes is perhaps as singular a figure among Western leaders as Portugal is unique among European democracies.

By pursuing his own idea of what its revolutionary democracy should be, he has managed over the years to anger or confound virtually every political group in the country--including at times the young military officers who launched the Portuguese revolution in 1974 and chose him two years later as their presidential candidate.

At the same time, polls indicate he is more popular than any other political leader in the country.

An Army general, Eanes (pronounced YAH-nesh), 46, keeps a Spartan office in the ornate Belem presidential palace outside Lisbon. In a recent, rare interview there he sat in a straight-backed chair and spoke quietly and intensely about his popularity in almost patriarchal terms.

The population has concluded, he said, "that I have democratic aims, and that I've always tried to act with legal and political coherence. I've always rejected favoring any of the parties, even when conflicts arise among them. I've always assumed responsibility for attitudes I thought were good for the Portuguese people, even when the political costs were high."

Those "attitudes" form no readily discernible ideology. But they have resulted in actions over the years that included the reappointment of a number of high-level military officers to posts within the revolutionary hierarchy, over the objections of the young officers who had thrown them out; the dismissal of the Socialist government in 1978, despite what Socialist leader Mario Soares says was a pledge to support him; and unbending opposition to attempts by the currently governing Social Democrat-Christian Democrat coalition to dismantle what it sees as some of the more deadening revolutionary laws.

Opposition to Eanes has been one of the few factors on which Portugal's leading political currents could unite. Last month, they joined forces to approve constitutional revisions limiting his powers to veto their laws, run the armed forces and dismiss the government at will.

"They wanted to maintain the picture of a presidential system, but take all the power out of the hands of the president," said Eanes' adviser, Vitor Alves. If he had chosen to challenge the action, "the only thing he could do about it was dissolve the parliament, or quit."

Eanes' supporters say the revisions were tailor-made to obstruct the current president, and that the parties will be sorry once his term is up three years hence. He is barred from running again.

Eanes is now reduced to pro forma vetoes of most government actions, sure to be overridden by parliamentary vote. But he has used them with a vengeance, at least putting himself on public record in opposition.

The biggest political question in Lisbon these days is no longer if, but when, the president will form his own political party and take them all on, perhaps calling parliamentary elections before their 1984 due date.

Socialist leader Soares scornfully says Eanes thinks of himself as "the new Juan Peron," after the Argentine populist who was short on ideology but long on blue-collar appeal that some defined as neo-fascism. Eanes says Soares engages in "hyperbole."

It remains an open question what a "presidential" party would stand for, and even Eanes' partisans note that he is "not a man of initiative."

But the people appear to trust him, and the kind of calm sureness, however ill-defined, and stability that he has come to represent during recent years of political turmoil.

What Portugal needs, Eanes said, is an "open, clear democracy. It's difficult to get there through 'isms.' "