VATICAN CITY — The cavernous nave of St. Peter’s Basilica was nearly empty when Cardinal Timothy M. Dolan arrived Sunday morning, shortly after dawn, a fading moon still hanging in the sky, and red streaks of sunlight illuminating the facade.
Dolan, the archbishop of New York, is a morning person — most days, he likes to get up at 5 and walk or exercise before his morning prayers — and on this last quiet day before the process of selecting a new pope begins Monday, he was raring to go: to celebrate a Mass, to start the day, to begin the conclave.
‘‘I’m eager to get started,’’ he said. ‘‘Let’s go. Let’s go, let’s get home.’’
Dolan is one of 115 cardinal-electors expected Monday morning at the Vatican’s New Synod Hall, along with dozens of retired cardinals who are invited to participate in the conversations but who cannot vote in the ensuing conclave because they are over 80.
The cardinals plan to meet for several days in what they call ‘‘general congregation’’ to get to know one another and to discuss issues facing the church globally; during their meetings, they will also pick a start date for the conclave.
Dolan, 63, is known for his upbeat, affable personality, but he is also a determined defender of Catholic orthodoxy. As president of the US Conference of Catholic Bishops, he has spoken out against a White House mandate for birth control coverage in health insurance.
‘‘The only thing we’re certainly not prepared to do is give in,’’ Dolan said at a national bishops’ meeting last November. ‘‘We’re not violating our consciences.’’
As he prepares for the papal conclave, Dolan has been stressing the importance of preserving the church’s traditions.
Dolan, who was named a cardinal just a year ago by Pope Benedict XVI, spent seven years in Rome as rector of the North American College, where he had studied for his own ordination years earlier.
A St. Louis native, Dolan attended a seminary prep school in Missouri and earned a doctorate in church history in 1985. After working as a parish priest, professor, and seminary leader, he served briefly as an auxiliary bishop in the Archdiocese of St. Louis. In 2002, Pope John Paul II appointed him archbishop of Milwaukee.
In 2009, Benedict named Dolan archbishop of New York, the nation’s second-largest archdiocese after Los Angeles, serving about 2.5 million Catholics.
Over the last several days, Dolan has been meeting with other church officials, doing interviews with reporters, and taking care of more ordinary tasks. On Saturday he visited a friend in the hospital and on Sunday he took New York’s seminarians and priests in Rome to lunch.
Dolan has said, ‘‘I never like to come to Rome without saying Mass at St. Peter’s sometime during my stay,’’ so on Sunday that is what he did.
He employed a small chapel in the basilica’s grottoes, and invited about 20 people, including members of the New York news media, to take part. Anne Thompson, an NBC News correspondent, was a reader during the liturgy.
“We’re all here to follow the extraordinary events with the departure of Benedict XVI, the election of a new successor of St. Peter,’’ Dolan said. However, he said, the celebration of Mass is more significant.
‘‘We’ve got to keep in mind — you know what, even more important than the pope is what we’re doing right now,’’ he said. ‘‘The life of the church goes on, and the life of the church centers around what we’re doing right now.’’
He celebrated the Mass in the Chapel of Our Lady Queen of the Hungarians. Dolan, a fan of sports metaphors, noted that the chapel was ‘‘just a 9-iron shot from the tomb of St. Peter.’’
In his brief homily, the cardinal made a passing reference to the shooting at Sandy Hook Elementary School in Newtown, Conn., saying that in biblical times people tried to discern what God was doing, just as people today look at the massacre and ‘‘try to figure out what happened,’’ or try to understand God’s role in ‘‘tragedy and sickness and suffering in our own life.’’
Those are understandable questions, the cardinal suggested, but, he said, ‘‘Don’t try to be figuring out God’s will out there all the time — try to figure out what God is asking you to do inside.’’