BARNSTABLE, Massachusetts — Eunice Kennedy Shriver, a sister of President John F. Kennedy and a longtime champion for the disabled, was in critical condition Friday at a Massachusetts hospital.

The 88-year-old Shriver's husband, children and grandchildren gathered at her side at Cape Cod Hospital in Barnstable, said family spokesman Stephen Rivers.

California Gov. Arnold Schwarzenegger, the husband of Shriver's daughter, Maria, was also there, said Aaron McLear, a spokesman for the governor.

Shriver has been weakened in recent years by a series of strokes. She lives in Hyannis Port, near the family compound where her brother, U.S. Sen. Edward Kennedy, has been staying as he undergoes treatment for brain cancer.

Sen. Kennedy left the compound Friday in a golf cart with his wife and dog, headed toward the area where the family sailboat is docked.

Shriver is the fifth of the nine Kennedy children. Edward Kennedy and Jean Kennedy Smith are her sole surviving siblings.

In an recent interview posted on eunicekennedyshriver.org, Sen. Kennedy said his sister has never backed down from the rest of competive clan.

"She always strived to be the best, and she in many respects has made such an extraordinary difference in the lives of so many people around the world," he said.

Shriver is perhaps best known for her work to establish the Special Olympics, inspired in part by the struggles of her mentally disabled sister, Rosemary.

She organized the first Special Olympics in 1968 in Chicago. The two-day event drew more than 1,000 participants from 26 states and Canada. By 2003, the Special Olympics World Summer Games, held that year in Dublin, Ireland, involved more than 6,500 athletes from 150 countries.