Mayoral control of New York City's schools is set to expire this evening unless state legislators can reach a deal.

Thanks to the vagaries of state law, the structure for managing New York City's schools is decided by the legislature in Albany. The Democrat-controlled Assembly, the majority of which is friendly with teachers unions, passed a bill in May tying mayoral control to other routine matters like extending property and hotel taxes. The bill was an effort to remove the issue from the political football status it has held since shortly after Mayor de Blasio took office in 2014. Senate Republicans, though, want to keep the ball in play. In recent years, they've used de Blasio's power over the schools as a cudgel to force him to accept more charter schools with fewer restrictions on what they can do with public resources, and that seems to be the issue once again this go-round.

Former Mayor Michael Bloomberg got the current system put in place in 2002, and enjoyed six- and seven-year stretches of school oversight without state interference. De Blasio, who backed a failed effort for Democrats to retake the state Senate in 2014, seems to have been punished for his political pedigree, getting only one-year extensions for the last two years. Each time, Senate Republicans extracted concessions for the charter industry.

In 2015, the legislature increased the number of charter schools that can open in New York City from 25 to 50, and struck limits on how many charters could be authorized by each of the state's authorizing bodies. Last year, lawmakers made it easier for charter schools to switch authorizers. The successive measures help charter companies, many of which dislike the requirements of the city Department of Education, switch to one of the other two authorizers, the State University of New York or the state Board of Regents.

Last week, as talks ground on and the de Blasio administration began to sound the final alarm about the impending calamity, Governor Cuomo said that he saw a compromise as a three-year extension and "a charter school component."

Senate Majority Leader John Flanagan has said simply that he wants more charters. His own district in Suffolk County, the Village Voice notes, contains no charter schools.

Senate Majority Leader John Flanagan, center right, and Governor Cuomo (Kevin P. Coughlin/Governor's Office)

Even the most extreme conservative voices on this issue—the long-shot Republican mayoral candidate Paul Massey who says that de Blasio has "utterly failed New York kids," and the New York Post editorial page—aren't seriously arguing that the city should return to its former system of school governance. If mayoral control lapses, the city will again have a Board of Education with members appointed by the mayor and the five borough presidents. A reboot of the system would cost the city $125 million to $160 million a year, according to a Mayor's Office estimate, largely because of the greater staff the decentralized system requires. It would also subject the city's schoolchildren to the machinations of borough-level politicians, while leaving the disempowered mayor still responsible for the schools' budget.

“If they don’t [renew mayoral control], the entire system will slide back into the old, decentralized structure we had before," school Chancellor Carmen Fariña wrote in Chalkbeat. "That would mean chaos, gridlock and corruption."

Speaking today, de Blasio said of the impending expiration, "This is D day, it’s zero hour."

This may be a bit hyperbolic. Mayoral control did briefly expire in 2009, prompting Bloomberg to push borough presidents to appoint pro-status quo board members. The board met once, for under 10 minutes, long enough to reselect then-Chancellor Joel Klein. The board began to plan for community school board elections the following spring, but the state soon got around to reinstating mayoral control and that wasn't necessary.

Experts widely predict a similar outcome should mayoral control momentarily lapse this go-round, but City Hall officials warn that nothing is guaranteed.

That said, why, beyond political retribution, are out-of-town Republicans so bent on micromanaging New York's education system?

"What is driving this conversation is Sen. Flanagan’s belief that every child deserves a first-class education, regardless of what school you attend," said Scott Rief, a spokesman for the Senate majority leader, "regardless of whether or not your parents have means."

That is one explanation.

There are currently over 200 charter schools in New York City, many of them in majority minority neighborhoods, representatives of which are overwhelmingly Democrats. The schools take a variety of forms and have a variety of track records. Their unifying characteristic is that they're privately run, don't have to abide by union rules, and don't have to take all comers. And that rich people love them.

Megarich people like hedge funder Paul Singer, right, pictured with Mitt Romney, have poured millions into New York state politics to promote charter schools. (Chip Somodevilla/Getty)

In recent years the state Republican Party has benefited from millions in campaign spending by massively wealthy charter school supporters including hedge fund managers, the Wal-Mart heir Walton family, and David Koch, among others. In turn, state GOP legislators have steered billions into charter schools, often at the expense of students in their districts, which tend to have few or no such schools.

Rief declined to say whether Flanagan is again pushing to raise the cap on charter school openings, saying only that "we believe that charter schools are an integral part of education in New York." He said that Flanagan cares about the minutia of New York City's school system because "those children that attend New York City schools, 1.1 million students, are residents of New York state. Of course we would care about that."

The Independent Democratic Conference, a breakaway group of eight Democratic senators that caucuses with the Republicans, is also heavily backed by the charter industry, having received hundreds of thousands in contributions from many of the same oligarchs since 2011.

The IDC supports charter school expansion and does not seem to back Assembly Democrats' bill that would tuck mayoral control in with tax extensions. But, spokeswoman Candice Giove said, leader Sen. Jeff Klein has introduced his own bill seeking to expand the input and eligibility requirements for local community education councils, thereby giving parents more say over what happens in their kids' schools.

"Senator Klein believes mayoral control creates a system of accountability that must be continued for our public school children and continues to hold discussions to accomplish this goal," Giove wrote in an email . "Donations play no role whatsoever in the legislative process."

Unlike expanding support for charters, increased community input in schools has not been a major topic of public discussion around the current mayoral control standoff. That's sad, according to Columbia University sociologist Amy Wells, because parents care about community control too.

The horse-trading "makes me sick to my stomach half the time, because it's really not about their constituents—it's about power and the power play," Wells said. "In education there's much more power and money behind some reforms and not other reforms."

She continued, "This discussion about mayoral control and what it should be moving forward is a really important one. But I think that holding it hostage to [expanding charter schools] is not in the best interest of the public."

Governor Cuomo, an ally of the IDC since its creation, has often been reluctant to support Democrats, and has also taken millions in contributions from charter supporters. He has largely stayed on the sidelines of the mayoral control debate, saying that he supports the system, but not publicly exerting any pressure to protect it.

The Governor's Office did not respond to an email seeking comment.