BRAINTREE — Cardinal Sean P. O’Malley said today he was “kind of blindsided” by Pope Benedict XVI’s decision to retire while in office, and jokingly dismissed the suggestion that he might be chosen as the new leader of the Roman Catholic church.

“I haven’t lost any sleep about it,’’ O’Malley told reporters during an afternoon news conference at the Boston archdiocese’s headquarters here. “And I have bought a round-trip ticket so I’m counting on coming home.’’