The death of premier Francisco Sa Carneiro removes from Portuguese politics its most confrontational personality, a man who did not hesitate to clash with the ambassador of the United States or the president of the republic if they stood in his way.

So Carneiro raised confrontation to a high art, and when he did not get his way, he would resign from whatever post he happened to hold. He was threatening to repeat that tactic if his candidate did not defeat the incumbent President Antonio Ramalho Eanes in the two-round elections that start Sunday.

The death in a plane crash of the man often referred to as "the fighting cock" may permit Portuguese politics to return to a natural bent for consensus -- often symbolized by the custom in bullfighting rings there of never killing the vanquished beast.

Sa Carneiro's unconventional place in the public life of devoutly Roman Catholic Portugal was underlined by his open companionship with Snu Bonnier Abecassis, the Danish-born divorcee who died at his side in yesterday's crash.

The premier rallied the dispirited northern Catholic peasantry, the conservative middle class and the traditionalist elements of an Army that had been largely radicalized in the "revolution of the carnations" of 1974 that overthrew the 50-year-old dictatorship founded by Antonio Oliverio Salazar.

Taking advantage of the public's weariness with five years of leftist rhetoric, Sa Carneiro engaged in what seemed to be almost a deliberate provocation by insisting that the tiny People's Monarchist Party be included in the electoral coalition he led to victory in parliamentary elections a year ago.

Sa Carneiro, whose divorce from his pious wife of many years had not yet been pronounced under Portugal's time-consuming divorce procedures, might have run for president himself in a less Catholic country.But even he apparently recognized that he could not flout that convention.

So, he sent a conservative general, Antonio Soares Carneiro (no relation) to do battle with his arch-rival, President Eanes. In one of those paradoxes with which Portuguese politics abound, the Socialist- and Communist-backed incumbent made his mark as a general heading the forces that turned back the Communists when their drive to take over the state seemed unstoppable.

When Sa Carneiro came to power a year ago, what divided him from Eanes was not so much political philosophy as a determination to be the undisputed man in charge. The electorate apparently recognized this. After twice giving a clear mandate to Sa Carneiro's Democratic Alliance in less than a year, the polls indicated that despite all the political fights he picked with Eanes and his threat to quit if the president were reelected, the voters were preparing to confirm Eanes in power.

In 1973, in his first successful use of the tactic of resigning, Sa Carneiro stunned politicians by quitting the dictatorship's rubber-stamp parliament after Salazar's successor refused to accept the restoration of civil liberties. The move turned out to be shrewdly timed. tWhen the revolution came a year later, he had a reputation for liberalism and courage that allowed him to emerge as a leader.

He formed the Social Democratic Party and applied to the Socialist International for membership alongside Mario Soares' regular Socialist organization. Soares prevented that maneuver.

Those in Sa Carneiro's party who still hankered for a center-left coalition got their comeuppance when their leader forced them out by twice resigning and getting himself twice reelected stronger than ever as party leader.

The diminutive Sa Carneiro engaged in a complex clash of personalities with the equally short U.S. ambassador of the time, Frank Carlucci. The conflict boiled down to Sa Carneiro feeling slighted that the embassy would not give him what he considered his due because it underestimated his future importance.

When asked recently whether he was not overplaying his hand against Eanes, So Carneiro reportedly replied, "Until now, I've always bet and I've always won."