Cardinal Godfried Danneels of Belgium suggested John Paul might step aside next year, now that he has achieved his dream of leading the church into the new millennium.
Mere mention of the issue has angered the Vatican, which sees such talk as seeking to weaken the papacy. Reaction to Danneels' suggestion was swift.
``This is the personal opinion of Cardinal Danneels, which we do not confirm,'' said a one-line statement issued Thursday by the pope's spokesman, Joaquin Navarro-Valls.
Danneels, who has been mentioned as a possible successor to John Paul, is the highest-ranking churchman to go public with the thought, which has been on the minds of many given the pope's frail condition.
A top German bishop, Karl Lehmann, broke the ice in February when he said he thought the pope would step down if he thought he could no longer lead the church.
John Paul will be 81 in May. His speech is slurred and his hands tremble, both symptoms associated with Parkinson's disease, a progressive neurological disorder. Since hip surgery following a fall in his bathroom in 1994, he has had difficulty walking and climbing stairs.
He looked weak when he received Queen Elizabeth II at the Vatican on Tuesday, needing a cane for support. While the queen's voice rang clear, the pope's was barely audible.
Danneels' comments were reported by Belgian and Italian media from advance excerpts from a book ``Frankly Speaking. Six Conversations with the Cardinal,'' to be released Monday.
Speaking about the retirement age for bishops of 75, the cardinal said, ``I wouldn't be surprised if the pope also retired after 2000. He absolutely wanted to reach the Jubilee year, but I believe he would retire afterward,'' according to published reports.
There is precedent--Pope Celestine V, who abdicated in 1294. He spent the last two years of his life in confinement because his successor feared he could become the rallying point for a schism.
While church law provides for a papal resignation, there is no procedure to declare incapacity.