The 95-year-old was admitted at Suburban Hospital in Bethesda on Sunday, the family said in an e-mail statement attributed to spokeswoman Kirsten Seckler.
No other details about his ailment were released. Shriver announced in 2003 that he had Alzheimer’s disease.
He served as the first Peace Corps director in the administration of his brother-in-law, President John F. Kennedy. He also was Democrat George McGovern’s running mate in 1972.
Shriver’s wife and Special Olympics Founder Eunice Kennedy Shriver died in 2009 at age 88.
He is also the father of former NBC reporter Maria Shriver, who is married to former California Gov. Arnold Schwarzenegger.
The handsome Shriver is often known first as an in-law. But his achievements are historic in their own right and changed millions of lives: the Peace Corps’ first director and the leader of President Lyndon Johnson’s “War on Poverty,” out of which came such programs as Head Start and Legal Services.
Within the family, he was sometimes relied upon for the hardest tasks. When Jacqueline Kennedy needed the funeral arranged for her assassinated husband, she asked Shriver.
Shriver had fought for integration in Chicago and helped persuade Kennedy to make a crucial decision in the 1960 campaign despite other staffers’ fears of a white backlash: When the Rev. Martin Luther King Jr. was jailed in Georgia that fall, Kennedy phoned King’s wife and offered support. His gesture was deeply appreciated by King’s family and brought the candidate crucial support.
Soon after taking office, President Kennedy named Shriver to fulfill a campaign promise to start the Peace Corps. Although it was belittled by some as a “kiddie corps,” Shriver quickly built the agency into an international institution.
In 1994, Shriver received the Presidential Medal of Freedom, the nation’s highest civilian honor, from President Bill Clinton.
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