Pope Benedict XVI announced Monday that he would resign Feb. 28 - the first pontiff to do so in nearly 600 years. The decision sets the stage for a conclave to elect a new pope before the end of March.
Omaha Archbishop George Lucas said, "I have been as surprised as everyone else to learn that Pope Benedict XVI plans to resign at the end of this month. We see this decision, in the context of a lifetime of service to the Lord, as an act of great pastoral love for all of us in the Church. I remain grateful for his leadership and fatherly care. I invite all to pray for the pope and for the guidance of the Holy Spirit in this important time of transition."
The pope's brother, Georg Ratzinger, said the pontiff had been advised by his doctor not to take any more transatlantic trips and had been considering stepping down for months.
Georg said his brother was having increasing difficulty walking and that his resignation was part of a "natural process."
"His age is weighing on him," Georg said. "At this age my brother wants more rest."
The 85-year-old pope announced his resignation Monday in Latin during a meeting of Vatican cardinals on Monday morning.
He emphasized that carrying out the duties of being pope - the leader of more than a billion Roman Catholics worldwide - requires "both strength of mind and body."
"After having repeatedly examined my conscience before God, I have come to the certainty that my strengths due to an advanced age are no longer suited to an adequate exercise of the Petrine ministry," he told the cardinals. "I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only by words and deeds but no less with prayer and suffering.
"However, in today's world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith, in order to govern the bark of St. Peter and proclaim the Gospel, both strength of mind and body are necessary - strengths which in the last few months, has deteriorated in me to the extent that I have had to recognize my incapacity to adequately fulfill the ministry entrusted to me."
The last pope to resign was Pope Gregory XII, who stepped down in 1415 in a deal to end the Great Western Schism among competing papal claimants.
Benedict called his choice "a decision of great importance for the life of the church."
the move allows the Vatican to hold a conclave before Easter to elect a new pope, since the traditional mourning time that would follow the death of a pope doesn't have to be observed.
It will also allow Benedict to hold great sway over the choice of his successor. He has already hand-picked the bulk of the College of Cardinals - the princes of the church who will elect the next pope - to guarantee his conservative legacy and ensure an orthodox future for the church.
There are several papal contenders in the wings, but no obvious front-runner - the same situation when Benedict was elected pontiff in 2005 after the death of Pope John Paul II.
The Vatican stressed that no specific medical condition prompted Benedict's decision, but in recent years, the pope has slowed down significantly, cutting back his foreign travel and limiting his audiences. He now goes to and from the altar in St. Peter's Basilica on a moving platform, to spare him the long walk down the aisle. Occasionally he uses a cane.