He tells correspondent Ed Bradley that a spotlight on Bratton turns up the heat on the police chief to deliver on his promise to bring down the city's crime rate.
The mayor appears in a 60 Minutes profile of Chief Bratton.
"It's fine with me that Bill Bratton likes the spotlight, because anybody who likes the spotlight is going to be on the spot. They're going to have to deliver," says Mayor Hahn.
That challenge is also fine with Bratton. "That's right. If [diminished crime] doesn't happen, it's on me," Bratton says.
But it won't be easy to change a situation Bratton says is "worse" than he thought when he took the job. Acknowledging the disadvantage of not getting more manpower or money, Bratton says the job will "be very hard. It will take a long time."
Mayor Hahn isn't worried. "I'm absolutely convinced he will [cut crime] because, for him, failure is not an option," he tells Bradley. "I don't think anybody is going to be tougher on Bill Bratton than Bill Bratton."