Jackson called Schiavo's impending death "an injustice." He said he asked Schiavo's husband and guardian Michael Schiavo for permission to pray with Terri but was turned down.
Joining the conservatives who have rallied to the parents' cause, the liberal Jackson said he would call Florida state senators who opposed legislation that would have reinserted Schiavo's feeding tube and ask them to reconsider.
Jackson's arrival Tuesday was greeted by some applause and cries of "This is about civil rights."
"I feel so passionate about this injustice being done, how unnecessary it is to deny her a feeding tube, water, not even ice to be used for her parched lips," said Jackson, who has run for president as a Democrat. "This is a moral issue and it transcends politics and family disputes."
"I wanted the Reverend Jackson here for moral support," said Mary Schindler, Terri Schiavo's mother. "I feel good with him here. Very strong. He gives me strength."
Doctors said Terri Schiavo, 41, would probably die within a week or two when the tube was removed ten days ago. She suffered catastrophic brain damage in 1990 when her heart stopped for several minutes because of a chemical imbalance. Her husband contends his wife told him years ago she would not want to be kept alive artificially under such circumstances.
University of South Florida political science professor Susan MacManus said Jackson's appearance shows that the life-and-death issues surrounding their daughter resonate beyond white, Christian conservatives.
"A person of faith, and not just a white, conservative person of faith will be seen as a welcomed change," MacManus said.
Schiavo's father, Bob Schindler, said he visited his daughter Tuesday and said she was "failing."
"She still looks pretty darn good under the circumstances," Schindler said. "You can see the impact of no food and water for 12 days. Her bodily functions are still working. We still have her."
After Jackson's news conference, a man was tackled to the ground by officers when he tried to storm into the hospice, Pinellas Park police said.
Dow Pursley, 56, of Scranton, Pa., was shocked with a Taser stun gun and was arrested on charges of attempted burglary and resisting arrest without violence, police spokesman Sanfield Forseth said. The man had two bottles of water with him but did not reach the hospice door, police said. He is the 47th protester arrested.
On Monday, an attorney for Schiavo's husband said an autopsy will be performed after Terri Schiavo dies to show the extent of her brain damage.
George Felos, the attorney for Michael Schiavo, said that the chief medical examiner for Pinellas County, Dr. John Thogmartin, had agreed to perform an autopsy.
An attorney for Schiavo's parents, David Gibbs III, said her family also wants an autopsy. "We would certainly support and encourage an autopsy to be done, with all the unanswered questions," Gibbs said.
Felos said he had visited Schiavo for more than an hour Monday and said she looked "very peaceful. She looked calm."
"I saw no evidence of any bodily discomfort whatsoever," Felos said, although he added her breathing seemed "a little on the rapid side" and her eyes were sunken.
The parents on Monday pressed again for President Bush, Congress and the president's brother, Gov. Jeb Bush, to intervene to have the feeding tube reinserted. A small group of supporters protested outside the White House gates
President Bush's aides have said they have run out of legal options.
At least two more appeals filed by the state seeking the feeding tube's reconnection were pending, but those challenges were before a Florida appeals court that had rejected the governor's previous efforts in the case
Meanwhile, Philadelphia police said a man made a death threat to Michael Schiavo's sister-in-law.
The threat was made Monday morning in northeast Philadelphia by an unknown man. He approached Joan Schiavo, the wife of Michael Schiavo's brother, William Schiavo, as she was on her way to work. That's according to police Sergeant Andy Smith, who says the man called the woman a "murderer."
Smith said she replied politely, saying "You don't even know the family." Smith said the man replied, "Well, if Terri dies, I'm going to come back and shoot you and your family."
No arrests were immediately made, but police said they were taking the threat very seriously.