WASHINGTON — Unlike his brothers, Edward M. Kennedy has grown old in public, his victories, defeats and human contradictions played out across the decades in the public glare.

A loyal Democrat, this Kennedy challenged an incumbent president of his own party when he ran for the White House. He lost, then brought tears to the eyes of many in a packed Madison Square Garden that summer night in 1980.

"For me, a few hours ago, this campaign came to an end," he said at the age of 48. "For all those whose cares have been our concern, the work goes on, the cause endures, the hope still lives and the dream shall never die."

What dream, exactly, has never explicitly been spelled out by the 76-year-old Massachusetts senator, who doctors disclosed yesterday is suffering from a malignant brain tumor.

Arguably, Camelot ended the night of the concession speech 28 years ago, although as the only surviving male in a storied political family, Kennedy guards the legacy still.

It isn't only the mementoes that line the walls of his Senate office and Capitol hideaway — the pictures; the dog tags once worn by his brother, the president; the note from his mother admonishing him to watch his language in public.

He prays privately at the grave sites of John Kennedy and Robert Kennedy at Arlington National Cemetery, and his role is more public on occasion, as when John F. Kennedy Jr. died in 1999 in an airplane crash.

"We dared to think, in that other Irish phrase, that this John Kennedy would live to comb gray hair. ... But like his father, he had every gift but the gift of years," he said.

Instead, it turned out that with that concession speech in 1980, Kennedy charted a course for himself and in large part for his party for the next quarter century and more.

"I'm a Senate man and a leader of the institution," he said in a recent Associated Press interview.

From civil rights to immigration to healthcare to education, he placed his imprint on every major piece of social legislation that cleared Congress.

No mystery there. In a conservative era, if grand victory is impossible for a Democrat, and it almost always is, he settles for smaller steps to be built on later.

It has made him the bargainer of choice for Republicans seeking a willing partner on legislation.

Utah Sen. Orrin Hatch, the conservative Republican, issued a statement of best wishes yesterday — and appended a list of legislation they had successfully co-sponsored across the years.

There was the Orphan Drug Act of 1983, providing tax credits to encourage the development of medicines for rare diseases; a bill providing healthcare for children of the working poor; creation of the Ryan White AIDS Act to improve availability of care for low-income AIDS victims and their families; the landmark Americans with Disabilities Act and more.

"Sen. Kennedy has been an example, a shining example, as how he's crossed the aisle and sponsored so many legislative enactments," added Sen. Arlen Specter, R-Pa., on the Senate floor. "I've had the opportunity to co-sponsor the Kennedy-Specter bill, for example, on hate crimes, and the civil rights bill."

Along the way, Kennedy has irritated Democrats for his willingness to compromise. President Bush's No Child Left Behind Act is the most notable recent example.

As the most prominent liberal of his day, he has long been an easy and popular target for Republicans.

The automobile accident that resulted in the death of a young Pennsylvania woman, Mary Jo Kopechne, drew snickers both before and after it shadowed his presidential campaign. Later, as he aged, it was his girth, a problem neither of his brothers ever had to contend with.

Earlier this winter he endorsed Barack Obama over Hillary Rodham Clinton for the Democratic presidential nomination, then embarked on an ambitious schedule of campaign appearances.

He usually refers only sparingly to his assassinated brothers, John and Robert, in his public remarks, and his endorsement was cast in terms that aides said were unusually personal.

"There was another time, when another young candidate was running for president and challenging America to cross a new frontier. He faced criticism from the preceding Democratic president, who was widely respected in the party," Kennedy said. "And John Kennedy replied, 'The world is changing. The old ways will not do. ... It is time for a new generation of leadership.' "