Cardinal Jaime L. Sin, the powerful Roman Catholic archbishop of Manila who used his influence to champion the rights of the poor and rally the widespread popular resistance that brought down the presidencies of Ferdinand E. Marcos and Joseph Estrada, died early today in Manila, a spokesman for the cardinal said. He was 76.

A brother, Dr. Ramon Sin, said that the cardinal, who stepped down from the archdiocese in 2003 in poor health, died of renal failure, he told a television station in Manila.

Cardinal Sin led the nearly 40 million Catholics in the Philippines for almost three decades, through political upheaval that brought martial law, repressive dictatorship and democratic rule.

A round-faced, bespectacled man, he was known for his sense of humor that included poking fun of his own name. But it was through his withering and unwavering public criticism of the Marcos regime in the 1980's that Cardinal Sin became an international figure.