The president and Mrs. Bush are praying for Pope John Paul who the Vatican says is in very serious condition.
The president and Mrs. Bush join people around the world in prayers for the Holy Father, "The outpouring of love and concern from so many, including millions of Americans, is a testimony to his greatness. During this time, his Holiness is in the thoughts and prayers of us all."
Mr. McClellan says President Bush is being kept up to date on the pope's condition and the U.S. embassy to the Holy See is in close contact with the Vatican.
The president and the pope last met in Rome in June when Mr. Bush awarded the pontiff America's highest civilian honor for his moral leadership.
Mr. McClellan says it is not an appropriate time to speculate on whether Mr. Bush would attend the pope's funeral.
Vatican officials say his condition has deteriorated and his breathing is shallow.