Washington ? Former Sen. Daniel Patrick Moynihan, a New York City shoeshine boy who became an iconoclastic scholar-politician and served four terms in the Senate, died Wednesday. He was 76.

Moynihan’s death was announced on the Senate floor by Sen. Hillary Rodham Clinton, who two years ago was elected to the Senate seat Moynihan had held for 24 years.

“We have lost a great American, an extraordinary senator, an intellectual and a man of passion and understanding for what really makes the country work,” she said.

The New York Democrat died from complications stemming from a ruptured appendix at 4:15 p.m. Wednesday at the Washington Hospital Center, hospital officials said. He had undergone surgery on March 11 to remove his appendix, and was moved into intensive care later that week, suffering from infection and pneumonia.

The lanky, pink-faced lawmaker, who preferred bow ties and professorial tweeds to the Senate uniform of lawyer-like pinstripes, reveled in speaking his mind and defying conventional labels.

Known for his ability to spot emerging issues and trends, Moynihan was a leader in welfare reform and transportation initiatives, and an authority on Social Security and foreign policy.

His intellect, and his emphasis on principle before politics, won him the respect of both parties. In more than 30 years of watching the Senate, said former Senate Republican leader Trent Lott of Mississippi, “I have not known a more brilliant and a more erudite senator.”

President Bush described Moynihan as an “intellectual pioneer” who was “recognized for his commitment to free trade, Social Security, freedom for people around the world and equal opportunity for all Americans.”

Senate Democratic leader Tom Daschle of South Dakota said that “in many respects, Pat Moynihan was larger than life,” citing a description in the Almanac of American Politics that Moynihan was “the nation’s best thinker among politicians since Lincoln and its best politician among thinkers since Jefferson.”

Moynihan, said current New York Democratic Sen. Charles Schumer, was “a giant as a thinker, a giant as a senator and a giant as a human being.”

His office said a burial Mass is scheduled for March 31 in Washington, and he will be buried that day with full military honors in Arlington National Cemetery. Moynihan served in the Navy from 1944 to 1947.

Moynihan served in the Senate from 1977 to 2001. After retiring from politics, Moynihan became a senior scholar at the Woodrow Wilson Center. Fellow legislators named Manhattan’s new federal courthouse in his honor.