Sen. Edward Kennedy’s (D-Mass.) office sent out an update on his condition Monday morning, saying that the lawmaker had a “restful night” and will be “undergoing further evaluation.”

“It is unclear whether anything definitive will be known today or tomorrow, but the doctors will let us know when there’s something more to say about the cause of Saturday’s seizure,” Kennedy’s office said Monday.

Kennedy’s office also said that President Bush called Kennedy’s wife on her cell phone and sent his best wishes to the Senator, telling her to “take care of my friend.”

Kennedy, 76, was rushed to a Cape Cod Hospital at 9 a.m. Saturday from his family’s compound in Hyannis Port, Mass. He was later airlifted Massachusetts General Hospital in Boston.

Dr. Larry Ronan, Kennedy’s primary care physician at Massachusetts General, said in a statement Saturday:

“Preliminary tests have determined that he has not suffered a stroke and is not in any immediate danger. He’s resting comfortably, and watching the Red Sox game with his family. Over the next couple of days, Senator Kennedy will undergo further evaluation to determine the cause of the seizure, and a course of treatment will be determined at that time.”

First elected in 1962, Kennedy is the senior Senator from Massachusetts and the chairman of the Health, Education, Labor and Pensions Committee. He is the brother of the late President John F. Kennedy and Sen. Robert F. Kennedy.

– Erin P. Billings