WASHINGTON — President Bush, who had established a reverent and personal relationship with Pope John Paul II, mourned the pope's death Saturday with a brief televised statement at the White House.

Bush said his quarter century as head of the Roman Catholic Church and his lifetime of dedication to freedom and values made him a "hero for the ages."

"The Catholic Church has lost its shepherd. The world has lost a champion of human freedom," the president said. "A good and faithful servant has been called home," he added.

Bush was expected to travel to Rome for the funeral, but the White House held off making an official announcement of the delegation it would send out of respect for protocol. White House press secretary Scott McClellan said Bush aides expected to hear about funeral arrangements from the Vatican today and said it would be inappropriate to discuss the president's plans before then.

He and first lady Laura Bush later attended Mass at the Cathedral of St. Matthew the Apostle near the White House, surprising the congregation when they walked into the church moments before the service began.

At the cathedral Saturday evening, Cardinal Theodore McCarrick, archbishop of the Washington diocese, told the Bushes: "It was a very special grace that you came to pray with us tonight. I know your great affection for him, Mr. President, and I know he appreciated it."

It was a rare, unscheduled moment for the president, who was seated among hundreds of parishioners who had not been screened by security. Bush did not speak during the Mass but seemed to listen intently and nodded as McCarrick praised John Paul.

The pope and president were in agreement in their stand against abortion, with Bush borrowing the Vatican's terminology in his political arguments for support of a "culture of life" in America. But John Paul differed with Bush on Iraq, opposing the U.S.-led invasion of that country in 2003.

Sen. John Kerry of Massachusetts, Bush's foe in the November election, praised the pope Saturday as someone who "persevered through enormous suffering with inspirational dignity."

"We will never forget the example he set by forgiving the man who tried to take his life and by praying at the Western Wall to ask Jews for their forgiveness," Kerry added.

Congressional leaders added their tributes to a leader who, in the words of Senate Majority Leader Bill Frist of Tennessee, "revolutionized the papacy." House Speaker Dennis Hastert, R-Ill., called the late pope "a beacon of light around the world."

Elsewhere in the nation, a standing-room-only crowd in New Orleans' St. Louis Cathedral took solemn note of the pontiff's death.