The 76-year-old senator was "conscious, talking and joking with family," the spokeswoman told The New York Times. His wife, Victoria, his children and his niece, Caroline Kennedy Schlossberg, were reported to be with him.

Kennedy went to Cape Cod Hospital Saturday morning after feeling ill at his home in Hyannisport. He was then moved by helicopter to Massachusetts General Hospital.

Kennedy's primary care physician, Dr. Larry Ronan of Massachusetts General Hospital, issued a statement Saturday saying preliminary tests determined Kennedy had not suffered a stroke "and is not in any immediate danger. He's resting comfortably, and watching the Red Sox game with his family."

Ronan said Kennedy would undergo further evaluation to determine the cause of the seizure.

"Sen. Kennedy is resting comfortably, and it is unlikely we will know anything more for the next 48 hours," Kennedy's office said in a statement shortly after he was hospitalized.

Kennedy underwent surgery last October to clear his carotid artery to remove any potential threat of a stroke and his colleagues said he had been recovering nicely.