Susan Walsh, Associated Press
Sen. Edward Kennedy, D-Mass., is being treated at a Boston hospital. He underwent a procedure last year to widen a blocked carotid artery.

Edward Kennedy, a liberal Democratic icon of the Senate and the surviving patriarch of American political royalty, suffered a seizure Saturday at his home in Hyannis Port, Mass., and was rushed by helicopter to Massachusetts General Hospital in Boston, hospital officials said.

The 76-year-old senior senator from Massachusetts was awake and joking with his family by late afternoon, according to a source close to the Kennedy family who spoke on the condition of anonymity. By early evening, he was watching a Boston Red Sox game and ordering dinner from Legal Seafood, the source said.

Larry Ronan, Kennedy's primary-care physician, released a statement saying Kennedy was "not in any immediate danger."

"Senator Kennedy will undergo further evaluation to determine the cause of the seizure, and a course of treatment will be determined at that time," Ronan's statement said.

Further information on his prognosis is not likely until Monday, said a spokeswoman, Stephanie Cutter.

Ominous early reports that Kennedy had suffered strokelike symptoms Saturday morning gave way to more optimistic notes by afternoon. Senate Majority Leader Harry Reid, D-Nev., said he had spoken with Kennedy's wife, Victoria Reggie Kennedy, about 3:15 p.m., and confirmed he had not suffered a stroke.

Kennedy's condition was not life-threatening but was serious, Reid told reporters at the Nevada Democratic Convention in Reno. His wife told Reid the ailing senator "woke up fighting."

"The one thing I can say, if there ever was a fighter, anyone who stood for what we as Americans, we as Democrats, stand for, it's Ted Kennedy," Reid said.

Rep. Patrick Kennedy, D-R.I., Sen. Kennedy's son, was by his bedside, as was Caroline Kennedy, his niece. Sen. John Kerry, D, the junior senator from Massachusetts, visited the hospital.

Kennedy has had cerebrovascular disease. Last year, he underwent a procedure to widen a partially blocked left carotid artery, which supplies blood to much of the brain. The procedure is sometimes done preventively if the narrowing is severe enough; Kennedy's was described as "very high-grade" by his physician.

According to the source close to the Kennedy family, Kennedy woke up feeling ill, then suffered the seizure. His family called 911 and rushed him to Cape Cod Hospital, where he was flown by helicopter to Massachusetts General. Doctors ruled out a stroke in the afternoon.

A family friend said that Kennedy slumped at the breakfast table, where he felt disoriented and had some numbness in his face but experienced no paralysis or slurred speech. Doctors are exploring whether the episode is related to medications Kennedy has been taking since his surgery.

Kennedy's sudden illness elicited an outpouring of sympathy from Republicans and Democrats alike, including all three of the remaining candidates for president.

Sen. Barack Obama, D-Ill., whom Kennedy endorsed as the standard-bearer of President John F. Kennedy's legacy, said he spoke with the senator's wife.

"I have been in contact with the family. Obviously, they are in our thoughts and prayers," Obama said.

Sen. Hillary Rodham Clinton, D-N.Y., echoed the sentiment, as did Sen. John McCain, R-Ariz., the presumptive Republican nominee.

Kennedy was elected to the Senate in 1962, just two years after his brother, John Kennedy, was elected president and a year before his assassination.

He emerged as one of the Senate's most prolific legislators and successful dealmakers. He teamed with President Bush during Bush's first term to co-author the president's signature No Child Left Behind education legislation but broke dramatically with Bush over the invasion of Iraq and has been one of Bush's fiercest critics ever since.

His loss to then-President Jimmy Carter for the 1980 Democratic presidential nomination cemented his reputation as the champion of the party's liberal wing. Last August, he became only the third senator to have cast 15,000 votes.