The buses arrived in Lower Manhattan from Harlem, the Bronx and Brooklyn on Thursday morning, carrying thousands of charter school supporters who put on matching red T-shirts and came out to draw attention to what organizers called a crisis in the quality of New York City’s public schools. Some of the smallest protesters, squirming in T-shirts that stretched to their ankles, were less than four feet tall.  “The whole school came,” said Angela Sutherland, whose son, a student at Success Academy charter school in Crown Heights, Brooklyn, stood quietly by her side.  The rally at Foley Square, which included speeches by politicians and a performance by the musician Questlove, was part of a coordinated campaign, organized primarily by charter school advocates, to put pressure on Mayor Bill de Blasio as he and legislators in Albany develop their education agendas in the coming months.  Last fall, as Mr. de Blasio drew ahead in the race for mayor, a similar group of protesters marched across the Brooklyn Bridge in support of charter schools. While Mayor Michael R. Bloomberg was an enthusiastic promoter of charter schools, Mr. de Blasio’s support is far more muted and conditional.  This year, the campaign for charter schools has included a website, a social media campaign and a rally that drew thousands. But beyond drawing attention to the city’s struggling schools, it has not included specific, stated goals, like more charter schools, for example.  “We’ll need a truly bold strategy to ensure no child is stuck in a failing school, and as a result, we’re certainly broadening our focus,” said Jeremiah Kittredge, chief executive of Families for Excellent Schools, a charter advocacy group that played a key role in organizing the rally. So far, Mr. Kittredge said, the administration has only been “tinkering at the edges” of the problem.  There are a host of battles on the horizon for charter schools, however, including one over the limit on the number of charter schools allowed in the city, and a tug of war over providing classroom space for expanding charter networks.  Early Thursday morning, the de Blasio administration released a video that appeared to be a pre-emptive response to the accusations at the rally.  “We have a crisis when it comes to education,” Mr. de Blasio says in the video, as footage rolls of him eating at a lunch table with children. “The answer is not to find an escape route that some can follow and others can’t. The answer is to fix the entire system.”  On the south end of Foley Square, organizers distributed dozens of handmade signs, each painted with one of a few slogans, like “Great Schools Now” and “Don’t Steal Possible.” The buses, stocked with granola bars, fruit and bottles of water, had been hired to encourage parents and students from charter schools to participate.  Many parents said the schools made calls, texted and sent their children home with fliers to ensure a strong turnout. Teachers made speeches on the buses to outline for parents the talking points of the day.  Eva S. Moskowitz, the founder of the Success Academy charter network, delayed the opening of all 32 schools in her network so that children and their teachers could attend the rally. Children were required to be accompanied by a parent or guardian; those who could not make it had to make alternative child-care arrangements for the morning.  Mr. Kittredge said he did not know the full cost of the rally or the number of schools that had been closed or delayed to accommodate it.  The rally came one day after Schools Chancellor Carmen Fariña announced that the city would abolish a letter-grade evaluation system for city schools, a move the city promoted as doing away with oversimplified and often misleading information, in favor of more comprehensive information for parents. Mr. Kittredge, however, called the move a step back from accountability.  Charter schools receive public money but operate independently from the school system. They are often managed by nonprofit groups and have greater latitude in deciding on staffing, scheduling and curriculum than traditional district public schools. But they have passionate detractors who say that they operate with too little transparency for publicly funded institutions and that they offer an educational solution for only a fraction of students.  A version of this article appears in print on October 3, 2014, on page A21 of the New York edition with the headline: Charter School Backers Rally, Hoping to Influence de Blasio’s Policies. Order Reprints|Today's Paper|Subscribe
Demonstrators filled Foley Square to highlight what they said was a crisis of quality in New York City public schools.