Mayor Michael Bloomberg said Cathie Black was the perfect choice to head the city's 1.1 million-student school system because she was "a superstar manager."
But her resignation Thursday after three contentious months on the job was the latest in a series of third-term setbacks for Bloomberg and a defeat of his bid to hire a business-minded outsider like himself for a top job.
"I will take full responsibility for the fact that this has not worked out as either of us had hoped or expected," Bloomberg said at a hastily called City Hall news conference to announce Black's resignation. She did not attend.
Bloomberg surprised even some officials within his administration when he plucked the former publishing executive from the business world and installed her as head of the nation's largest public school system. Critics, including many parents of public-school students, assailed her lack of experience as an educator. She had no background as an educator, had never attended public schools and had not sent her own children to them.
On the job, Black failed to convince the critics they were wrong. Her few unscripted public appearances were marked by gaffes. Meeting with parents concerned about crowded schools, she joked that birth control was the solution. Faced with hecklers at a meeting about closing schools, she heckled back. Two polls put her approval rating at 17 percent.
Teachers at some schools erupted in cheers when the news of Black's resignation broke.
And now, Bloomberg has chosen a schools chancellor who is Black's opposite in many ways.
Deputy Mayor Dennis Walcott, 59, is a graduate of New York City public schools and hold's master's degrees in education and social work. A former kindergarten teacher, Walcott founded the Frederick Douglass Brother-to-Brother program, a mentoring program for boys.
As deputy mayor for education and community development, Walcott has been the highest-ranking black person in Bloomberg's administration. In that job, he oversaw the Department of Education, with its 1.1 million students in almost 1,700 schools, as well as the New York City Housing Authority, the Department of Youth and Community Development and the Mayor's Office of Adult Education.
Soon after Walcott was named as the new chancellor, more than a dozen public officials dashed off statements praising him for his education experience. Speaking to Department of Education staff members Thursday afternoon, Walcott alluded to his status as a role model for students.
He said that he visited a high school recently and the principal noted that when Walcott greeted a student, "he pulled up his pants and straightened up and stood a little taller."
Walcott said he would continue with the reforms introduced under Bloomberg.
"To me the great equalizer in society is ensuring that every child receives a quality education, especially a quality public education," said Walcott, himself a graduate of the city's public schools.
Bloomberg has a reputation as a fierce defender of his administration's top appointments, with the exception of Patricia Lancaster, whose abrupt departure as Buildings Department commissioner three years ago followed a string of 13 construction-accident deaths in only a few months' time.
On Thursday, the mayor stood behind Black's performance, saying, "I have nothing but respect and admiration for her and for the work she has done."
Speaking outside her home, Black told the TV station NY1 that she felt "fine" about the transition.
"It's been a great privilege to serve the city of New York and the mayor for three months," she said. "I have loved the principals and the teachers and the kids. Dennis Walcott is a great guy. We have a wonderful relationship and I wish everybody the best."
After she became chancellor in January, several department officials left. One of them, former deputy chancellor Eric Nadelstern, said that a lack of media access to Black led to relentless coverage of her slip-ups. Over time, it became clear that she had become a liability, he said.
"It is a very formidable ... learning curve, and I think she was still in that learning curve when City Hall determined that her time was up," he said.
Bloomberg's own approval numbers have been declining in recent months, as he has dealt with the aftermath of a flawed city response to a major blizzard and with public dissatisfaction with his handling of a city budget hampered by state and federal cutbacks. Dissatisfaction with the city's schools has figured in as well, although the majority of parents with children in the public schools say the schools are good or excellent.
Bloomberg said Thursday that he remained proud of what the Department of Education had accomplished in his more than nine years in office, and dismissed critics who might call the announcement of Black's departure an indication that his third term had derailed.
"The city continues to improve," he said.
Associated Press writers Karen Matthews in New York and Michael Gormley in Albany contributed to this report.