Gov. Bruce Rauner on Tuesday followed through on his promise to veto a school funding bill, taking aim at hundreds of millions of dollars in help for cash-strapped Chicago Public Schools.

The Republican governor, long a critic of CPS' leadership and the Chicago Teachers Union, rewrote the measure to strip out more than $200 million in grant money, penalize the district for its declining enrollment and make it appear wealthier in a complex new formula that determines how state school aid is distributed. And while Rauner left in $221 million in CPS pension help, he did so with a big string attached.

In unveiling his amendatory veto, Rauner tapped into a regional divide that has long seen Chicago pitted against the suburbs and Downstate. The governor argued that portions of the legislation that would benefit CPS amount to a "diversion" of hundreds of millions of dollars away from other schools, "unfairly hurting children across the state and unfairly advantaging one school district."

"There's an attitude that Chicago is the only community that has low-income students. This is false. Chicago is the only community that has English language learners. That's false. That Chicago is the only city with minority students who are disadvantaged students. That's false," Rauner said at a news conference in his Capitol office. "We have those children all around the state, and they all deserve to be treated fairly."

Democrats ripped Rauner, saying he's trying to play communities off one another to get re-elected next year and contending his veto raises the possibility that all districts may begin the school year without state funding.

"The only thing the governor's action advances is his own personal brand of cynical politics," Mayor Rahm Emanuel said. "It is well past time for Gov. Rauner to stop playing politics with our children's futures, start demonstrating leadership and ensure a child's education isn't determined by their ZIP code or his political whims."

Next steps

Rauner's veto sets the stage for weeks — and potentially months — of uncertainty, kicking the issue back to Democrats who control the General Assembly. The Senate now has 15 days to consider the veto, then the House gets another 15 days. If lawmakers don't agree with the changes or overturn them, the legislation dies and the comptroller's office will be unable to send schools their state aid payments until a compromise is reached.

The first checks are scheduled to be sent by Aug. 10. If that deadline is missed, it's unlikely many schools would be unable to open. However, some districts may have to cut back on programs, borrow or tap into reserves.

The stakes get higher as the days tick off the calendar, with pressure rising on lawmakers to do something to avoid angering parents who wouldn't be able to send their children to class while they go to work should schools close.

Some Democrats already have raised concerns about whether Rauner's changes go beyond the scope of what's considered constitutional for an amendatory veto.

Democratic House Speaker Michael Madigan, who helped write the 1970 Illinois Constitution, historically has taken a dim view when he thinks governors have overreached with an amendatory veto, citing a separation of powers. While Madigan in the past has declined to take up such legislation, the risk in not doing so this time is that the governor could blame him for schools not being funded.

Asked about Rauner's veto Tuesday, Madigan spokesman Steve Brown said he doesn't "know that the analysis has been concluded on that. That'll be an element of what goes on, and we will look to see what the thoughts are and what happens with some of the advocacy groups."

If legislators want to go along with Rauner's veto, they would need an extraordinary majority of three-fifths in the House and Senate. Speaking to reporters Tuesday, Rauner said it would require a simple majority. Later, a Rauner spokeswoman acknowledged the governor was mistaken.

Democrats held onto the bill for two months, sending it to the governor Monday, so now it will take 71 votes in the House to agree or override, and 36 in the Senate.

The math presents a political challenge. There are 37 Senate Democrats, more than enough to overturn Rauner. But there are just 67 in the House, meaning they must find Republican lawmakers to help like they did last month to override Rauner's vetoes of a tax hike and budget. Failing that, lawmakers would have to negotiate a new education funding plan with the governor.

"It's going to take some time, and the governor's actions today are going to extend the time that it takes to solve this problem," said Sen. Andy Manar, a Democrat from Bunker Hill who is a key negotiator.

Rauner's complicated amendatory veto is still being sorted out at the Capitol. Asked about the details, Rauner referred reporters to a website where his office had posted figures demonstrating how districts might benefit. That site was unavailable to the public on Tuesday, however, because it required a password.

Rauner's changes

While it's unlikely the governor's changes will become law as is, his rewrite gives some indication of the wish list Rauner will bring to the negotiating table as talks continue.

Among them:

•Hold harmless. Under the bill lawmakers approved, no school district would receive less than it did last year. New money above the $5 billion the state is supposed to pay out would first be sent to schools most in need.

Rauner would keep that so-called "hold harmless" provision in place until the 2020-21 school year, then switch the way funding is calculated from a per-district basis to a per-pupil basis. The upshot is that CPS and some Downstate districts that have seen declining enrollments stand to lose money.

CPS enrollment has declined precipitously the past five years amid a long decline in the city's birth rates, and also families moving out of Chicago or sending kids to private schools. Roughly 404,000 students were enrolled at CPS in the fall 2012, a figure that fell to 381,000 by fall 2016 and is expected to drop by 8,000 more this year.