(CNN) — R. Sargent Shriver, who was responsible for launching the U.S. Peace Corps after marrying into the Kennedy family and joining John F. Kennedy’s White House, has died, a family source told CNN.

Shriver, whose full name was Robert Sargent Shriver Jr., was 95. He had suffered for years from Alzheimer’s disease.

After overseeing the Peace Corps launch in the early 1960s, Shriver went on to serve subsequent presidential administrations and kept up his activism throughout his life, becoming a chief architect of President Lyndon B. Johnson’s war on poverty and later heading the Special Olympics, which was founded by his wife, Eunice Kennedy Shriver.

Shriver’s entree into the Kennedy family was Joseph P. Kennedy, the family patriarch, who hired him to run a business venture in Chicago. According to the Scribner Encyclopedia of American Lives, the work led to an introduction to Eunice Kennedy, whose siblings included JFK, Robert F. Kennedy and Ted Kennedy.

Shriver and Eunice Kennedy married in 1953.

Shriver served as JFK’s Midwest campaign manager for his 1960 presidential bid before heading the Peace Corps’ launch, which was seen as part of a new approach to the Cold War between the United States and the Soviet Union.

“He told me that everyone in Washington seemed to think that the Peace Corps was going to be the biggest fiasco in history,” Shriver told Time magazine in 1963 of Kennedy’s request that he head the program, “and it would be much easier to fire a relative than a friend.”

In 2011, the Peace Corps is celebrating its 50th anniversary. More than 200,000 volunteers have served in 139 counties on issues ranging from education to public health to environmental preservation through the program, according to the Peace Corps’ website.

After John F. Kennedy, his brother-in-law, was assassinated in 1963, Shriver was tapped by Johnson to launch the White House Office of Economic Opportunity, which comprised a handful of anti-poverty programs.

In a series of maneuvers that spoke to Shriver’s penchant for working across the political aisle, he served as Republican President Richard Nixon’s ambassador to France before becoming Democrat George McGovern’s running mate in 1972, as the two unsuccessfully tried to unseat Nixon.

McGovern named Shriver as his running mate after his first choice, Sen. Thomas Eagleton of Missouri, stepped down after revealing he’d had psychiatric treatment that included electroshock therapy.

In the 1980s and 1990s, Shriver served as chairman of the board of Special Olympics International, which Eunice Kennedy Shriver founded in 1968. The organization sponsors sports training and events around the world for people with intellectual disabilities.

Shriver, who was born in Westminster, Maryland, in 1915 and who graduated from Yale, also was long active in the Roman Catholic Church.

President Bill Clinton awarded him the Presidential Medal of Freedom in 1994.

Eunice Kennedy Shriver died in 2009.

The Shrivers had five children including Maria Shriver, the media personality and former first lady of California; and Timothy P. Shriver, who now heads Special Olympics International.