President Antonio Ramalho Eanes easily won reelection to a five-year term today, and the rightist government of Prime Minister Francisco Sa Carneiro, who died in a plane crash Thursday, reportedly will resign after an emergency meeting Monday.

With more than 70 percent of the vote counted, the National Election Center forecast that Eanes would win with 57 percent of the vote. Eanes needed to win more than 50 percent to avoid a runoff election with rival candidate Gen. Antonio Soares Carneiro (no relation to the late prime minister).

Soares Carneiro conceded defeat, calling the result "a popular verdict." He had received 39 percent of the tabulated votes. The remaining votes were scattered among four minor candidates.

Eanes, a former general backed by the Socialist and Communist parties, had led Soares Carneiro in pre-election polls by as many as 20 percentage points. But yesterday the state funeral for Sa Carneiro drew tens of thousands of mourners who turned the event into a massive political rally that raised the hopes of the rightists.

A sympathy vote for Soares Carneiro -- who had been hand-picked by the late prime minister to represent his majority Democratic Alliance coalition in the election -- did not materialize, however.

Earnes' victory could split the coalition government, which Industry Minister Alvaro Barret said would resign Monday. Barret said the coalition would try to form a new government later in the day. Eanes has the power to dismiss the government if the coalition is unable to form a new one. The Democratic Alliance had won a landslide victory in parliamentary elections just two months ago.

After the realignment of the government, Eanes will have to confront the major problems facing this country's young and fragile democracy.

During the next five years, he will be called on to steer Portugal into the European Common Market and to oversee the redrafting of the constitution's leftist slant.

The first task of the president will be to fill the power vacuum left by Sa Carneiro's death. The election -- the fourth national poll in the past year -- already has shown deep divisions in Portuguese society nearly seven years after the population joyfully welcomed a bloodless coup by a group of young officers against a 50-year-old dictatorship.

As Eanes went to vote in Lisbon, a woman shouted, "Murderer, murderer" at him, apparently reflecting an emotional belief among the Portuguese rightists that last week's plane crash was the result of sabotage. The government has ruled out sabotage in the crash.

Eanes, who was greeted by boos and applause as he entered the polling place, appealed for national unity after casting his vote. Sa Carneiro had supported Eanes when he won his first term of office in 1976, but later turned against him because the president obstructed the rightist overhaul of the Portuguese constitution, planned by the premier's majority Democratic Alliance coalition.

Sa Carneiro left no political heirs to head the Democratic Alliance -- a coalition of his own Social Democratic Party, with the Christian Democrats as junior partners and the backing of the small People's Monarchist Party.