Delicate Dance for Mayoral Candidates Seeking Support of Teachers" Union When Michael Mulgrew, the president of the city's teachers" union, looks out on a ballroom at the New York Hilton Midtown on Saturday, he will deliver a stinging speech about "mayoral dictatorship" and call for an investigation into 11 years of Department of Education data. Then, he will wait for his phone to ring. With a mayoral election less than six months away, candidates are rushing to win the backing of Mr. Mulgrew and his union, the United Federation of Teachers. They routinely call him to gush about his proposals, consult with him on drafts of speeches and accompany him on visits to schools as far away as Cincinnati. An unusual dynamic has unfolded as Mr. Mulgrew dangles a wish list of ideas - many of them meant to undo Mayor Michael R. Bloomberg's educational policies - and waits to see which candidates bite. On Saturday, Mr. Mulgrew will call for the next mayor to create a "truth commission" to investigate the city's data showing that graduation rates have improved and that the gap between white and minority students has narrowed. He will also propose restructuring a city department that oversees student testing and gives A-through-F grades to schools, a hallmark of Mr. Bloomberg's tenure. "When this administration wants to impose a new policy on our schools or score a political point, they just make the numbers fit and spin, spin, spin," Mr. Mulgrew will say, according to a copy of his prepared remarks. But denying the public the truth, especially when it comes to our children, only serves to make us all angry. The city's Department of Education said its statistics had been vetted by several independent research groups and that there was no need for a review. A spokeswoman for Mr. Bloomberg, Lauren Passalacqua, defended the mayor's approach. "This spectacle of candidates genuflecting at the altar of a narrow special interest group reveals the true threat to the hard-earned achievements of our students and teachers," she said in a statement. Mr. Mulgrew's acerbic words are likely to win cheers from his union's 200,000 members. But a more relevant test will be how enthusiastically the candidates actively seeking the union's endorsement embrace his ideas. On Friday, several Democratic candidates were quick to praise Mr. Mulgrew, although several stopped short of saying that they would adopt his proposals exactly as he envisioned. John C. Liu, the comptroller, said he liked the idea of a truth commission. "It's hard to believe some of the statistics that have been thrown around," he said. Bill de Blasio, the public advocate, said he supported an accounting of the effects of Mr. Bloomberg's educational policies, saying the mayor's approach had "vilified teachers" and "shut out parents." Christine C. Quinn, the City Council speaker, was more circumspect, saying she shared Mr. Mulgrew's interest in improving transparency. "It can't be that the mayor has more information than the teachers," she said. William C. Thompson Jr., a former comptroller, said he was receptive to Mr. Mulgrew's views. "We need to do much more to ensure that the Department of Education is an open book," he said. Joseph J. Lhota, a Republican candidate for mayor, declined to comment. Another Republican, John A. Catsimatidis, did not return a request for comment. In an interview, Mr. Mulgrew, president of the union since 2009, said he would endorse a candidate by mid-June. In his speech, he called for the next mayor to appoint a schools chief with an educational background, a position that all of the Democratic candidates except Ms. Quinn have endorsed. "I look at how they react to everything I say and this union says," he said, adding, "Nothing is a litmus test." Mr. Mulgrew said he would consider a variety of factors, including whether he thought the union's vast financial resources and network of thousands of volunteers could propel the candidate to victory. Securing the union's endorsement is a delicate endeavor - a charm offensive that has been in the works for several years. At a forum this week, the candidates struggled to name an instance when they had disagreed with the union. Mr. Thompson dredged up an issue from more than two decades ago - when the union opposed efforts to centralize the city's school system. Ms. Quinn agreed. Mr. Liu was the only candidate to name a more recent example, saying the union should have more aggressively supported the Khalil Gibran International Academy. The candidates must also balance pleasing the union while appealing to business leaders, many of whom consider Mr. Mulgrew a rogue figure whose chief concern is protecting the interests of teachers. Ms. Quinn, who is actively seeking the support of the business community, laughed when asked if she thought Mr. Mulgrew's position was extreme. In his speech, he suggests the administration has lied and compares the Department of Education to "Frankenstein castle." "Michael Mulgrew needs no help in his characterization or in his ability to express his feelings," Ms. Quinn said. Mr. Mulgrew said he was flattered by the attention. His aides joke that some candidates appear at the union's headquarters in Lower Manhattan so often that they have opened up offices in the building. "I'm a beer-in-the-backyard guy," Mr. Mulgrew said. It's not about the attention. They're all nice people.