Vatican City ? A wistful, ailing Pope John Paul II celebrated his 82nd birthday Saturday before thousands of cheering youngsters, but he could only muster reading a few lines of his speech before deferring to an aide.

The celebration capped a week in which two prominent cardinals said they believed the pope would retire if his frail health deteriorated to the point where he no longer could govern his church.

John Paul looked tired during the brief, public marking of his birthday in a Vatican auditorium, where a youth band played “Happy Birthday.”

Ushers wheeled the pope in and out of the auditorium on a platform, saving him from walking to center-stage. But the pontiff gathered enough strength to kiss a youngster.

“Thanks, so much thanks for your wishes,” John Paul told the crowd.

In a departure from his Vatican custom, John Paul read only parts of a two-page speech, leaving an aide to read the rest.

A hand tremor, slurred speech and difficulty in walking symptoms of Parkinson’s disease have plagued the pope for years, and doctors have told the pontiff to conserve his strength whenever he can.

Yet John Paul on Wednesday begins a five-day trip to Azerbaijan and Bulgaria, a pilgrimage that will test his stamina.

Just a few days ago, John Paul asked for spiritual support to help him continue his ministry leading the world’s more than 1 billion Roman Catholics.

He often has sounded short of breath during speeches lately. During Easter week services, he let other prelates carry out ceremonial duties while he sat near the altar.

On the eve of the birthday celebration, the Vatican’s No. 2 official, Cardinal Angelo Sodano, brushed aside talk of the pope’s resignation.

“The pope is at the helm of ship and all we who work at the (Vatican’s) Curia are at the oars,” Sodano, who is Vatican secretary of state, told Italian state TV.