However, papal spokesman Joaquin Navarro-Valls hinted a time might come when the Vatican has to reevaluate how to cope with a pontiff whose skill as a communicator, a hallmark of his 25-year papacy, is clearly declining.
"I work very close with him, and I see his mind, his capacity for projecting things, for putting new goals, which is absolutely intact," Navarro-Valls said in an interview with ABC's "Good Morning America." "So the problem is not there; at least it's not there yet."
When asked whether the Vatican would have to deal with the problem later if it became necessary, he said: "I suppose so."
John Paul has had trouble speaking for several years as a result of Parkinson's disease, which causes him to slur his words. Recently, however, he has occasionally been unable to deliver his full speeches, often only saying a line or two before turning the text over to an aide to finish.
The change was most evident during his September visit to Slovakia, where for the first time in over 100 foreign trips the pope was unable to complete his arrival speech. As recently as last week, however, John Paul managed to get through his comments, albeit with great difficulty.
Cardinals who are gathering in Rome for celebrations surrounding John Paul's 25th anniversary as pope on Thursday said that even though he has such difficulty speaking, he shows no sign of stepping down or turning over leadership of the Roman Catholic Church.
"He still seems to be able to do it," Cardinal Theodore McCarrick, archbishop of Washington, D.C., said. "As long as God lets him do it, he's going to continue doing it."
When asked whether the pope might step aside if he can no longer speak, McCarrick said he couldn't put himself in the mind of the pope.
"I do believe that this Holy Father is so much in the hands of God, he's going to let God tell him."
John Paul himself has made clear he does not intend to resign, saying he will carry out his mission to the end.
Portuguese Cardinal Jose Saraiva Martins, head of the Congregation of the Causes of Saints, told the Portuguese newspaper Diario de Noticias that only the pope can decide what he would do if he loses the ability to communicate.
"Evidently it would have to be evaluated, it would have consequences, but it wouldn't be fundamental for the pope's work," he was quoted as saying. "The word is very important for those who govern, but the Holy See is governed more by the head than by the word."
Cardinal Pio Laghi of Italy, a top papal envoy, said that even as John Paul loses his ability to speak, he remains lucid and able.
"He doesn't feel incapacitated at all," the AGI news agency quoted Laghi as saying Tuesday. "He governs with his mind and his heart."
But McCarrick conceded that the pope's inability to communicate effectively must be frustrating for a man who appeared on stage in his youth, can speak several languages and has always made a point of addressing the faithful in their native tongues.
"It must be so hard for him," McCarrick said. "Because I remember 25 years ago, he strode across the stage of the world and he was so eloquent and he could speak so beautifully in so many languages. It must be so hard, but he keeps going, (saying) 'Give me the next page, I'm going to read it.'"