BOSTON -- Speaking to The Pilot March 4, Cardinal Seán P. O'Malley confirmed that he hand-delivered a message from Boston Mayor Martin Walsh to Pope Francis inviting the Holy Father to the city.

It was the first time the cardinal spoke publicly about the invitation.

The cardinal said Mayor Walsh gave him the letter in February.

"I was kind of taken by surprise. I didn't realize he was going to do that, so I had to sit down and write my own letter of invitation, because I didn't want the mayor's to be the only invitation," Cardinal O'Malley said.

Cardinal O'Malley -- considered the pope's closest North American adviser -- traveled to Rome Feb. 15-Feb. 25 for a meeting of the council of eight cardinals advising the pope on reform of Church governance. There, he presented the Holy Father with both letters.

"I have no idea whether the Holy Father will be able to accept our invitation. Obviously, it would be a great joy for us," the cardinal said. "The Holy Father told me right at the beginning of his pontificate that he does not plan to travel as much as his predecessors had done."

Although it has not been officially announced, it is expected that Pope Francis will make a trip to the U.S. for the 8th World Meeting of Families that will be held in Philadelphia in 2015.

"If he does that, it might mean that he would visit other places in the United States, and Boston has put our oar in the water," Cardinal O'Malley said.

Reports by Antonio M. Enrique and Gregory L. Tracy contributed to this story.