Most of Stringer’s Supporters Have Fled. Not the Teachers’ Union.

The United Federation of Teachers is boosting Mr. Stringer’s embattled campaign with an advertising blitz.

In the weeks since a former campaign volunteer accused Scott M. Stringer of sexual misconduct, many of the Democratic mayoral candidate’s most crucial supporters, including the Working Families Party and a phalanx of progressive politicians, have abandoned his campaign. But powerful teachers’ unions are not only sticking with Mr. Stringer, the city comptroller — they are, starting Tuesday, offering a much-needed boost to his embattled campaign in the form of a multimillion-dollar advertising blitz. The American Federation of Teachers, the country’s second-largest teachers’ union, and the United Federation of Teachers, its large and influential New York City chapter, are the primary backers of the $4 million television and digital advertising effort. The ads and mailers will be paid for by NY 4 Kids, a super PAC created to “keep the issues affecting our schools, kids and teachers front and center in this election,” according to a release from the group.