Senator Ted Kennedy collapsed during the inaugural lunch for President Barack Obama yesterday.
The brother of John F Kennedy and Democrat grandee was one of two senators taken ill during the event.
Mr Kennedy was wheeled out of Washington’s Capitol building on a stretcher following what is believed to have been a seizure, witnesses said.
Mr Obama said: “I would be lying if I said right now a part of me is not with him. It’s a joyous time but also a sobering time. My prayers are with him and his family.”
Last year it was announced that Mr Kennedy had been diagnosed with a brain tumour. He has since undergone brain surgery.
The 76-year-old attended Mr Obama’s oath-taking on the Capitol’s west front earlier in the day.
During the lunch, the newly sworn-in president called attention to Mr Kennedy, saying “I know that while I was out of the room, concern was expressed about Teddy.”
Mr Obama added: “I think that’s true for all of us. This is a joyous time. But it’s also a sobering time. And my prayers are with him and his family and (Kennedy’s wife) Vicki.”
One eyewitness said Mr Kennedy was conscious when he left the luncheon on a stretcher.
A spokeswoman at the Washington Hospital Centre later confirmed that Mr Kennedy was awake and answering questions.
His wife and son, Democratic representative Patrick Kennedy, were said to be with him at his bedside.
Doctors later said Mr Kennedy's seizure was due to tiredness.
Dr Edward Aulisi, Washington Hospital Centre's neurosurgery chairman, said the senator was awake, talking with family and friends and feeling well.
He added: “After testing, we believe the incident was brought on by simply fatigue.”
It is expected that Mr Kennedy will leave hospital tomorrow morning. Meanwhile Democratic Senator Robert Byrd of West Virginia (91) was taken out of the room about the same time Kennedy was removed, said former Vice President Walter Mondale, who was sitting at a table with Byrd and Kennedy.
Democratic leadership aides said later that Byrd was fine and was seen at a Senate office building. Byrd is the oldest current member of the United States Congress.
He is also the first politician in US history to serve as a US senator for a state for 50 years uninterrupted.\[Michael Hall\]Byrd is President pro tempore of the United States Senate, a position that technically puts him third in the line of presidential succession, behind Vice President Joe Biden and House Speaker Nancy Pelosi.
He also held this post previously from 1989–1995, briefly in January 2001, and from June 2001-January 2003.