School will be closed tomorrow for 9,000 students at Success Academies, New York City's most prominent charter school chain. Instead of class, the charter schools -- which operate as government-funded public schools -- will bus their students to Albany for a political rally that happens to coincide with the lobbying day of the school's biggest foe, the United Federation of Teachers.

The move to shut down schools drew criticism last year, when Success first sent its students to an political rally that had been scheduled to clash with a rally a few blocks away held by New York City Mayor Bill de Blasio, who had opposed the expansion of Success. And like last year, attending the rally is essentially the only option for for students: the schools aren't providing alternative childcare. (Success told Capital New York that teachers, who are also required to attend, will instruct students on the bus.)

"I still have a deep belief that no public school system should be closed for a political rally," said Daniel Dromm, a New York City council member. "These students and parents don't have a choice."

Tomorrow's rally is organized by the nonprofit Families for Excellent Schools, which said that more than 160 charter schools would be represented at the rally. Charters and their supporters hope to encourage New York lawmakers to raise the state's cap on charter schools, which has put a stopper on the rapid growth of Success and other charters. Success plans to open 14 new schools this year, on top of the 32 that it already runs in the city, but will not be able to open any new schools in 2016 unless the cap is raised.

The rally's organizers argued against the idea that charter students would be missing out on class time because of the rally, given that charters traditionally have significantly longer school days than public schools.

"Most of these charter schools could hold a rally that lasted for a month and still give their students more days in the classroom than district schools hampered by a failing, self-interested bureaucracy," a representative of Families for Excellent Schools told BuzzFeed News.

Not coincidentally, the United Federation of Teachers will use tomorrow to lobby against raising that charter cap. The New York teachers' union argues that charters unfairly divert money from traditional public schools.

Success is backed by some of the state's most prominent figures, from Wall Street billionaires Dan Loeb and Paul Singer to former journalist Campbell Brown to Governor Andrew Cuomo, who made a surprise appearance at last year's rally. The school has also racked up impressive test scores, managing to dramatically outscore students in the city and in many of the state's wealthiest school districts.

But its use of students in political protests has some questioning its approach. "They're doing this to get a show of numbers," said Councilman Dromm. "If we were to close New York City public schools, we could bus in a million people, but we have an educational philosophy that says we don't do that."