Veteran Socialist leader Mario Soares was sworn in as Portugal's first civilian president in 60 years today in a ceremony that symbolized the end of military tutelage over the democracy that emerged 12 years ago from a leftist Army coup known as "The Revolution of the Carnations."

Vice President Bush, French President Francois Mitterrand and Spanish Prime Minister Felipe Gonzalez were among visiting dignitaries at the inauguration.

The 61-year-old Socialist, three times prime minister since 1974, narrowly defeated a right-wing opponent supported by the conservative government in a two-round presidential election earlier this year. He has abandoned the leadership of his Socialist Party and pledged in his inaugural address to support the minority government of Prime Minister Anibal Cavaco Silva despite ideological differences.

Soares succeeded Antonio Ramalho Eanes, a left-leaning Army general, whose two terms as president were a pillar of stability during Portugal's first turbulent decade of democracy, in which 16 governments fell before their terms were completed. Eanes is expected to assume the leadership of the newly formed Democratic Renewal Party, which holds a pivotal position in the National Assembly.

In his keynote speech to the assembly, Soares said his election marked "the end of Portugal's transition to a genuine democracy."

Soares is the country's first civilian president elected by universal suffrage. A military "council of the revolution," which had powers to veto legislation, was abolished during Eanes' second term.

Soares' comeback after a crushing defeat for his party in a legislative election last October was seen as an encouraging signal by Socialists throughout southern Europe. But his term could lead to a stalemate with the conservative government similar to what Mitterrand may face if the right wins next week's French assembly elections.

Soares promised the center-right government of Cavaco Silva, who toppled him from the premiership in the October election, his "loyal support and understanding." He said his main aim was to ensure political and social stability as conditions for capitalizing on Portugal's entry to the European Community.

The Social Democratic government holds only 88 of 250 parliamentary seats, and the prime minister has expressed concern that Soares' election could encourage the opposition to block his program of reducing the state's economic role. But analysts said opposition parties were unlikely to provoke an early election -- particularly the Socialists, who must find a leader to succeed Soares -- while the government maintains its effectiveness.

Cavaco Silva has made clear that he is not prepared to temper his hard line despite his fragile position in the assembly. He has condemned what he called attempts by the opposition to force the government to surrender its executive powers to the assembly. Such moves included a successful bid by the pro-Soviet Communists to make the government hold a parliamentary debate on its refusal to lower the cost of gasoline despite the drop in world oil prices.

Soares' role as president will be crucial to Portugal's stability if such clashes provoke a political impasse. The president has no powers to initiate or block legislation other than a delaying veto. But he is the country's supreme political arbiter, who can call elections or appoint new prime ministers to resolve crises.