New York City Schools Chancellor Carmen Farina officially announced her retirement Thursday after four years on the job.

Farina has had a long career in public education and actually came out of retirement for the chancellor position - a job Mayor Bill de Blasio describes as one of the toughest in the country.

Farina is widely credited for helping roll out universal pre-K, one of the mayor's signature achievements. While delivering remarks about her retirement, the chancellor said she's had an amazing team of support over the past four years. She also said that she never took her job to be loved or to win a popularity contest - but that she did it to work for the kids of the city.

"I came in this job to be respected and to be understood so people would be motivated to do what I think is best for the children of the City of New York," she said. "Our family engagement has never been higher."

De Blasio says a national search is underway for a replacement and that an announcement will be made in the near future.