One man threatened to marshal 1,000 votes against any elected official who dared to disagree with him. A woman who took an opposing stance was warned about making enemies. Another was so distressed she broke down in tears in front of her 4-year-old.  The issue causing so much anger and consternation: where children will go to elementary school in a section of the Upper West Side. New York City has proposed to move some blocks out of the zone of a popular school, Public School 199, which is mostly white and well off, into that of a lower-performing nearby school, Public School 191, where the students are largely poor and black or Hispanic. The city hopes to achieve a more diverse racial and economic mix at the schools, as well as relieve overcrowding at P.S. 199.  The debate is now stretching into its second year — the city dropped its effort last year amid protests. It has grown, if anything, more rancorous, with local elected officials castigating City Hall for not listening to parents’ concerns.  “I’m just livid,” Assemblywoman Linda B. Rosenthal, a Democrat, said at a meeting about the rezoning on Wednesday evening, admonishing Education Department officials not to think they could “pull the wool over everyone’s face.”  While Mayor Bill de Blasio, a Democrat, and the schools chancellor, Carmen Fariña, have been criticized for not being forceful enough in desegregating the city’s schools, the rezoning battle illustrates how difficult any change can be. Thrown into the mix are questions about property values, race, the meaning of community, the roots of academic achievement and how to tell if a school is safe.  The loudest outcry has come from residents in a handful of buildings whose children go to P.S. 199, and in particular two locations, 165 and 185 West End Avenue, which are part of an eight-building complex known as Lincoln Towers. Under the plans being discussed, the two buildings would be rezoned for P.S. 191.  Residents of the two buildings have turned out in scores at the meetings — there have been eight since June. They have said it makes no sense to divide the complex and pointed out that the proposed zone line does not follow a street but cuts through their backyard. They have argued that Lincoln Towers is responsible for the success of P.S. 199 because so many residents have attended the school. They have claimed that the two buildings produce an average of only six kindergarten students per year, so including them in P.S. 199 should not be difficult.  And they have not shied from making threats.  Gary Ramsay, a parent at P.S. 199, made the comment about rounding up 1,000 votes in a comment on a petition at Change.org. He also warned, “whatever else we can influence will go for whomever their opponents are next elections cycle.”  Ms. Rosenthal and the local state senator, Brad Hoylman, a Democrat, protested with residents of Lincoln Towers on Saturday. Representative Jerrold Nadler, a Democrat, has also taken their side. When asked about the goal of making schools more diverse, Mr. Nadler suggested in an interview that new buildings currently going up in the neighborhood be put in the 191 zone instead. “You can put them into 191 and accomplish the same goal,” he said.  So far the Education Department has not given in, but it has wavered. At the Wednesday meeting of the District 3 Community Education Council, the elected body that will vote on the zone lines, the department presented a new draft rezoning plan.  The president of the council, Joe Fiordaliso, said that the department was still considering the zone lines “right up until they made their presentation.”  It is not clear how much City Hall has been drawn into the deliberations, but some have suggested that the controversy could hurt Mr. de Blasio’s re-election efforts in what is known as a vote-rich neighborhood.  The city comptroller, Scott M. Stringer, an Upper West Side resident who is seen as a potential challenger to Mr. de Blasio, was withering in an interview on Thursday.  “This process is just a continuing failure on the part of D.O.E. and this administration to engage local, neighborhood stakeholders,” he said, adding that “if it wasn’t for Linda Rosenthal, no one would have any voice in that district.”  In addition to shifting the zone lines between P.S. 199 and P.S. 191, the department is pondering other moves. A new school building is being built near P.S. 191’s current home, and P.S. 191 will move there next year, as a way to give it a new start. The department will either open a new school in the former P.S. 191 building or move an existing school, Public School 452, which now shares a building on West 77th Street, into it.  The advantage of moving P.S. 452, from the department’s perspective, is that it is already established and popular, so parents in its new zone — which would combine parts of the current zones of P.S. 199 and P.S. 191 — would be likely to embrace the school.  P.S. 452’s principal and teachers support the move. Many current parents, however, have expressed distress at the idea.  Even if one of the plans goes forward, it is hard to know if parents who are rezoned to P.S. 191 will send their children there. Parents have expressed fear about the school’s low test scores and that it was on the list of the state’s most persistently dangerous schools last year. The principal, Lauren Keville, who started in 2014, has introduced a new writing program, and scores on the state reading test improved. (Math scores, however, fell.) The school came off the persistently dangerous list this year.  At the hearings in the face of harsh comments about the school, Ms. Keville, teachers at P.S. 191, and the presidents of the parent-teacher association have spoken up at times to defend the school.  On Wednesday, after several parents voiced dismay at the prospect of being rezoned to P.S. 191, Mr. Fiordaliso asked Ms. Keville to speak.  “I just want to say, I encourage you to come and actually see our school and see the wonderful things that are happening for our kids,” Ms. Keville said, her voice shaking slightly. “There’s a lot of misconceptions.”  Because of an editing error, an earlier version of a picture caption with this article misidentified a school on the Upper West Side. It was P.S. 452, not 199.  A version of this article appears in print on September 30, 2016, on page A22 of the New York edition with the headline: Rezoning Proposal for a City Elementary School Draws Anger From All Sides. Order Reprints| Today's Paper|Subscribe
New York City is trying to change school zone lines on the Upper West Side, but after countless meetings addressing the proposals, a consensus has not been reached.