BOSTON – Sen. Edward M. Kennedy was airlifted to a hospital Saturday after suffering a seizure at his home, and did not appear to have had a stroke as initially suspected, his spokeswoman said.

The 76-year-old Democrat, the lone surviving son in a famed political family, was undergoing tests at Massachusetts General Hospital to determine the cause of the seizure, spokeswoman Stephanie Cutter said.

Associated Press Sen. Edward M. Kennedy of Massachusetts. Video A source says Senator Ted Kennedy of Massachusetts has been hospitalized with apparent stroke-like symptoms. The 76-year-old Democrat's been in office since November 1962. Media Player The FREE Windows Media Player is necessary to play Windows Media.

“Senator Kennedy is resting comfortably, and it is unlikely we will know anything more for the next 48 hours,” she said.

Kennedy went to Cape Cod Hospital on Saturday morning “after feeling ill at his home,” Cutter said. After discussion with his doctors in Boston, Kennedy was taken to Massachusetts General.

An official who declined to be identified by name, citing the sensitivity of the events, had earlier said that Kennedy had stroke-like symptoms. The hospital declined to comment on his condition.

In October, Kennedy had surgery to repair a nearly complete blockage in a major neck artery. The discovery was made during a routine examination of a decades-old back injury.

Candidates' reactions Reaction of the presidential candidates to Sen. Edward Kennedy's hospitalization: “I have been in contact with his family. Obviously they are in our thoughts and in our prayers. Ted Kennedy is a giant in American political history. He's done more for health care than just about anybody in history. We are going to be rooting for him. I insist on being optimistic about how it's going to turn out.” – Sen. Barack Obama, D-Ill., who spoke to reporters in Eugene, Ore.    “My thoughts and prayers are with Sen. Ted Kennedy and his family today. We all wish him well and a quick recovery.” – Sen. Hillary Rodham Clinton, D-N.Y., in a statement.    “I was very sorry to hear that Senator Kennedy has taken ill, and like millions of Americans, Cindy and I anxiously await word of his condition. Senator Kennedy's role in the U.S. Senate cannot be overstated. He is a legendary lawmaker, and I have the highest respect for him. When we have worked together, he has been a skillful, fair and generous partner. I consider it a great privilege to call him my friend. Cindy and I are praying for our friend, his wife, Vicki, and the Kennedy family.” – Sen. John McCain, R-Ariz., in a statement.

The hourlong procedure on his left carotid artery – a main supplier of blood to the face and brain – was performed at Massachusetts General. This type of operation is performed on more than 180,000 people a year to prevent a stroke.

The doctor who operated on Kennedy said at the time that surgery is reserved for those with more than 70 percent blockage, and Kennedy had “a very high-grade blockage.”

On Saturday, Hyannis Fire Lt. Bill Rex said a 911 call came in from the Kennedy family compound at 8:19 a.m. A man was transported to Cape Cod Hospital and transferred by air at 10:10 a.m. from Barnstable Municipal Airport to Boston.

David Reilly, a spokesman for Cape Cod Hospital, said that Kennedy was brought to the hospital around 9 a.m. and stayed for about an hour before being flown by helicopter to the Boston hospital.

Sen. John Kerry of Massachusetts did not talk to reporters when he arrived at the hospital shortly after 1 p.m.

Kerry later issued a statement, saying that Kennedy “been a fighter who has overcome adversity again and again with courage, grit, and determination. Teresa and I are praying” for Kennedy's family.

“We know that everyone in Massachusetts and people throughout the nation pray for a full and speedy recovery for a man whose life's work has touched millions upon millions of lives,” the statement said.

Kennedy, 76, has been in the Senate since election in 1962, filling out the term won by his brother, John F. Kennedy.

Kennedy is the lone surviving son in a famed family. His eldest brother, Joseph, was killed in a World War II airplane crash. President John Kennedy was assassinated in 1963 and his brother Robert was assassinated in 1968.

Democratic presidential candidate Barack Obama, beginning a tour of hospitals in Eugene, Ore., told reporters that he had been in touch with the senator's family.

“Ted Kennedy is a giant in American political history. He's done more for health care than just about anybody in history. We are going to be rooting for him. I insist on being optimistic about how it's going to turn out,” he said.

Obama's rival for the Democratic nomination, New York. Sen. Hillary Rodham Clinton, also issued a statement.

“My thoughts and prayers are with Ted Kennedy and his family today,” she said. “We all wish him well and a quick recovery.”

Kennedy gave Obama's presidential campaign a big boost this year with his endorsement and has campaigned actively for the Illinois senator.

Kennedy was preparing to host the annual Best Buddies Challenge event on Saturday afternoon, a fundraiser for the Best Buddies organization founded by Anthony Kennedy Shriver that helps people with intellectual disabilities.

Hundreds are expected to participate in the event, which started with a 100-mile bicycle ride from the Kennedy Library in Boston to Hyannisport, and closes out with a concert at the Kennedy compound.

A man walking by Massachusetts General was startled by the news when he asked about the reason for the large media presence.

“Ted? Is he all right? Jeez, I'm taken aback. I just saw him on television yesterday,” said Jerry Leonard, 76, a retired bartender.

“He's a Kennedy. His name is synonymous with this area. I'm a Bostonian, too, and he's done a lot for us around here and for the senior citizens in particular. I don't know him but I feel a connection.”