Speaking at a Black church in Brooklyn last September, Andrew Cuomo tested the message that would quickly become the centerpiece of his campaign to be mayor of the country’s largest city. “We’re on the decline,” the former New York governor said. “Things are …

Ever since he was elected state attorney general in 2006 and especially during his nearly decade-long stint as governor, Cuomo has cultivated an image of himself as someone uniquely adept at managing…