Brazilian President-elect Tancredo de Almeida Neves spent most of his 50 years in public life battling for democratic rule in a republic more accustomed to demagogues and military men.

He died today, at 75, on the eve of what many hope will be Brazil's most open political era in two decades.

The veteran politician who had survived five military governments and a half dozen national political crises succumbed to multiple infections and complications following seven abdominal operations in less than three weeks.

Elected by a 686-member electoral college Jan. 15, Mr. Neves would have been this nation's first civilian president since the Army took power here in 1964. Mr. Neves himself had dubbed this forthcoming period as "the new republic."

The phrase is an effort to distinguish not only from the last two decades of military governments, but from the early part of this century, when the country was run by an "old republic" of landed gentry and autocrats.

Mr. Neves was born and reared during the height of the old republic, and lived to see the end of Brazil's longest period of military rule. Trained as a lawyer, he began his political career in 1934 when, at age 23, he was elected city councilman in his mountainous hometown of Sao Joao del Rei, in the central state of Minas Gerais.

His first taste as an adult of rule by strongman came early when, in 1937, populist dictator Getulio Vargas suspended democratic institutions.

Fifteen years later Vargas, in his second term as president, would choose Mr. Neves, then a federal deputy, to be his justice minister. In the tumult of the next few years, the young Cabinet minister developed a reputation as a skillful negotiator and a conciliator in times of political crisis. As pressures mounted against Vargas' unpopular measures, Mr. Neves resisted attempts to oust him by politicians and the military until Vargas committed suicide in 1954.

Mr. Neves went on to serve in a number of administrative posts, including head of the national development bank and a director of the Banco do Brasil, before returning to politics as a federal congressman.

Mr. Neves once again helped to quell a coup attempt when, in 1961, president Janio Quadros abruptly resigned and the Army sought to block the succession of left-leaning vice president Joao Goulart. Mr. Neves negotiated a compromise in which Goulart would assume the presidency with reduced powers and Mr. Neves would be named prime minister.

Brazil's brief parliamentary interlude lasted until 1964, when the Army ousted Goulart and initiated what would become the country's longest stretch of military rule. In those years, many politicians who opposed the military were stripped of their political rights or exiled. When the Congress was revived, however, Mr. Neves was there, working from within to restore democratic government.

A conservative, tight-lipped politician, Mr. Neves nevertheless always sided with Brazil's opposition. He also was careful to maintain cordial relations with the Army-backed Social Democratic Party.

Mr. Neves was a devout Catholic who was said to have been the lantern-bearer in the Good Friday procession through his hometown for 35 years. Elected the state's governor of Minas Gerais in 1982, he stood firmly behind last year's popular movement to restore direct elections for president.

When Congress failed to muster the two-thirds majority necessary to change the constitution, the opposition decided to challenge the military government head-on and named Mr. Neves as its candidate in the electoral college, a body that had been created to rubber-stamp the generals' choice for president.

Mr. Neves' opponent, wealthy federal congressman Paulo Maluf, was so unpopular he was frequently pelted with tomatoes in public and often had to be rescued by security guards.

Dozens of Social Democratic legislators defected to Mr. Neves' camp. The result: his Democratic Alliance rolled up a crushing 480-to-180 victory in the electoral college.

It was often said that Mr. Neves had waited 50 years for this opportunity, when he could personally oversee Brazil's transition to full democratic government.

It was Mr. Neves' tireless conciliation that galvanized Brazil's myriad dissident forces into a sturdy alliance in favor of democratic reform and civilian rule. If Mr. Neves' fledgling "new republic" is to survive, however, the country will have to rely less on the mending magic of a single, powerful leader and more upon the force of barely tested democratic institutions.

Mr. Neves is survived by his wife, Risoleta; three children, and more than 70 grandchildren and great-grandchildren.