ROME — An ailing Pope John Paul II is expected to appear briefly today on a video link-up during a Good Friday ceremony in the Colosseum to commemorate Jesus' march to his death on the cross.

If the past few days are any guide, the pope will look frail and pained. He will not speak. The fingers on his left hand will be mottled with purple bruises.

Amid reports that he is not recovering well from recent surgery to put a breathing tube in his throat, the pontiff, 84, has been unable to attend Holy Week ceremonies for the first time in his 26-year papacy.

What he has done instead is attempt to offer his deteriorating body, wracked by the complications of Parkinson's disease and the infirmities of old age, in mute testimony to the proposition that all human life has value.

"My thoughts turn to you, dear priests, as I spend this time recuperating in hospital, a patient alongside other patients, uniting in the Eucharist my own sufferings with those of Christ," the pope wrote during his hospital stay in a message to priests that was released yesterday, Holy Thursday.

On Sunday and again Wednesday, he appeared without speaking in his apartment window next to St. Peter's Basilica, his face twisting in obvious distress as he waved to onlookers. Yesterday, he watched Mass through a video link-up, Vatican officials said.

This year, each service has been handed over to a senior cardinal. On Easter Sunday, the principal Mass will be officiated by Cardinal Angelo Sodano, an Italian who as secretary of state is, in effect, No. 2 at the Vatican. Tomorrow's nighttime Easter Vigil, when Christians symbolically watch for Christ to rise from the dead, will be led by Cardinal Joseph Ratzinger.

The Italian news agency Apcom reported this week that the pope had been vomiting, suffering strong headaches and not responding well to his medications.

For some, the picture of a pope struggling against incapacitation is timely, coming as it does amid the controversy in the United States over whether to end the life of Terri Schiavo, the severely brain-damaged woman whose feeding tube has been removed.

Others see no connection and disagree with recent statements by Vatican officials that withdrawing life support from Schiavo is cruel and immoral.

To the pope's many admirers, his decision to present his suffering to the world, in what appears to be a last act of his papacy, is a deeply noble endeavor.

"We live in a world where pagan images of consumerism, egoism and overabundance are valued, where the sick and aged are marginalized, a world that wants to sweep aside those with limitations and eliminate the handicapped," said Cardinal Julian Herranz of Spain, one of only two cardinals from Opus Dei, a conservative order that John Paul holds in especially high esteem. "By contrast, the pope shows us that life has dignity until the last moment."

Not everyone is convinced that the Catholic Church is benefiting from an ailing John Paul remaining in office. Some think he should resign, something no pope has done willingly since the 13th century. (Celestine V stepped down in 1294, while Gregory XII reluctantly abdicated in 1415.)

"It will injure the Church if the pope cannot fulfill his function," the Rev. Michael Buckley, a noted theologian who chairs the Boston College theology department, recently told National Catholic Reporter columnist John Allen Jr. "The primacy of the pope is one of jurisdiction, of teaching and governing, and it's essential for the life of the church."

Buckley said John Paul could offer his message of redemptive suffering just as well if he stepped down. The pope's decline, he said, raised questions about who was actually making decisions in the Vatican.

John Cornwell, a professor at Cambridge University in England, put it more bluntly in "Pontiff in Winter," his recent critical biography of John Paul's later years: "During the pope's illness, the church has been run increasingly by his Polish secretary and a handful of aging reactionary cardinals."

In St. Peter's Square, where hundreds lined up to enter the basilica yesterday, there was a range of opinions.

Joe Salerno of Roxbury Township, N.J., who was visiting with his wife and daughter, said he did not think papal resignation was called for yet.

"I think that in the current condition he's in, he can run the church," Salerno said.

Just being near the pope "does make you get in touch with your Catholic roots," Salerno said. "We may agree or disagree with various things about the church like most American Catholics, but being here for Easter is just a blessing."

Most Europeans are not devout churchgoers, even in Catholic countries such as Spain and Italy. Two young Spaniards strolling through the square, Carolina Castellanos, 25, and her sister Magdela, 27, said they were not here to see the pope but to see the splendor of Rome.

Others said the pope was very much in their thoughts. Lola Montalban, 32, of southern Spain, stood with a group of fellow students, clutching a rosary and praying for John Paul.

"We came here to be next to him, because this could be his last Holy Week," she said. "He can't take part in the Masses, but as always, he knows how to unite his pain and suffering with the cross of Christ."

John Paul could not possibly step down, she said, because "the pope is a father to the church, and a father cannot resign."