BALTIMORE — Facing a reignited crisis of credibility over child sexual abuse, the Roman Catholic bishops of the United States came to a meeting in Baltimore on Monday prepared to show that they could hold themselves accountable.

But in a last-minute surprise, the Vatican instructed the bishops to delay voting on a package of corrective measures until next year, when Pope Francis plans to hold a summit in Rome on the sexual abuse crisis for bishops from around the world.

Many of the more than 350 American bishops gathered in Baltimore appeared stunned when they learned of the change of plans in the first few minutes of the meeting.

They had come to Baltimore wanting to prove that they had heard their parishioners’ cries of despair and calls for change. Suddenly, the Vatican appeared to be standing in the way, dealing the bishops another public relations nightmare.