When Barack Obama's presidential prospects sagged, Sen. Edward Kennedy lifted the candidate with a coveted endorsement.
When brain cancer kept the Massachusetts Democrat from delivering his stepdaughter's college commencement address, Obama left the campaign trail and stood in for his then-Senate colleague.
And when Obama made one of the most closely watched decisions of his young presidency -- the type of puppy for his daughters -- it was Kennedy who gave him "Bo," a Portuguese Water Dog like the pair that have been a fixture in Kennedy's Capitol Hill offices.
With Kennedy now at his vacation home in Hyannis Port on Cape Cod and Obama setting off on his weeklong stay on nearby Martha's Vineyard, there's speculation the president may come see the ailing senator.
A visit could provide a rallying point for Democrats as Obama seeks to achieve one of Kennedy's career goals: overhauling the U.S. health insurance system to provide near-universal coverage.
It also would show anew the close relationship between the first African-American president and the last vestige of the Camelot White House era of the early '60s.
Despite a gulf in age, race and life experience, the 48-year-old Obama and the 77-year-old Kennedy have forged a personal bond evident in the tribute the president paid Kennedy and his assassinated brothers, President John F. Kennedy and Sen. Robert F. Kennedy, before he signed the Edward M. Kennedy Serve America Act into law in April.
"I want all Americans to take up that spirit of the man for whom this bill is named; of a president who sent us to the moon; of a dreamer who always asked, `Why not?' -- of a younger generation that carries the torch of a single family that has made an immeasurable difference in the lives of countless families," Obama said.
Those who know both men find the relationship understandable, despite the age difference.
"He is the kind of president that Kennedy can relate to," said Robert Shrum, who helped drafted the senator's famous 1980 Democratic National Convention concession speech and remains a close personal friend.
"He's trying to do very, very big things. He's appealed to people's idealism. He's appealed to their notion of service, things that have been touchstones of Kennedy's life," Shrum said.
Capitol Hill aides say the two men were not especially close during Obama's first 18 months in the Senate, which began in 2005. They shared a mutual bond in opposing the Iraq war, but there was little more than a collegial relationship.
The turning point came in 2006, when Obama visited Kennedy to ask whether he should run for president.
"Your time only comes once, and this is your time," Kennedy told Obama, according to a Kennedy aide who spoke on condition of anonymity to recount a private conversation.
During the following months, Kennedy avoided endorsing any Democratic contender, including New York Sen. Hillary Rodham Clinton. She had been first lady under another Kennedy acolyte, former President Bill Clinton.
Yet Kennedy's admiration for Obama, coupled with a feeling the Clintons had incited racial concerns about Obama, led Kennedy to endorse Obama in January 2008. He and his niece, Caroline Kennedy, evoked parallels to the early 1960s excitement surrounding the presidency of her father, John F. Kennedy.
"I've seen it. I've lived it. And with Barack Obama, we can do it again," the senator said during a raucous rally at American University in Washington.
On May 17, 2008, Kennedy suffered a seizure at his home in Hyannis Port. It was the result of a terminal brain tumor.
Unable eight days later to deliver the commencement address to his stepdaughter and her classmates at Wesleyan University, Kennedy asked Obama to speak in his place.
"It is rare in this country of ours that a person exists who has touched the lives of nearly every single American without any of us even realizing it," Obama told the graduates. "And I have a feeling that Ted Kennedy is not done just yet."
Indeed, Kennedy returned to the Capitol in July 2008 to cast the tie-breaking vote on a Medicare bill. Medicare is the government-run health insurance program for seniors.
The next month, Kennedy cast aside concerns from doctors about exposure to crowds and made a surprise, 7-minute speech for Obama at the Democratic National Convention in Denver. "The work begins anew. The hope rises again. And the dream lives on," he said, repeating lines Shrum wrote for him in 1980.
And Kennedy was there on Capitol Hill again in January, despite the frigid weather, at Obama's inauguration.
At a luncheon afterward, Kennedy suffered a seizure. Obama went backstage to deliver his best wishes before the senator was taken away by ambulance.
"I would be lying to you if I did not say that right now a part of me is with him," an anguished Obama said when he took the podium. "This is a joyous time, but it's also a sobering time."
The new president invoked Kennedy again in February, during his first speech before a joint session of Congress. He urged the House and Senate to pass the Kennedy public service act. They did so within Obama's first 100 days in office.
In March, Obama led a "Happy Birthday" sing-a-long at a Kennedy Center party for the senator. And during a visit to the Vatican in July, he hand-delivered a letter the senator wrote to Pope Benedict XVI.
Most recently, Obama awarded Kennedy the nation's highest civilian honor, the Presidential Medal of Freedom.
Kennedy could not attend the Aug. 12 ceremony, which occurred the day after his sister, Eunice Kennedy Shriver, died. Obama made the award to the senator's daughter, Kara.
"The life of Sen. Edward M. Kennedy has made a difference for us all," the president said.