With the state on the path to blowing a Thursday deadline to deliver funds to schools across Illinois, the state Senate is bringing lawmakers back to Springfield on Sunday in an effort to override Gov. Bruce Rauner’s veto of an education funding measure.

Although senators will be in session Sunday, it’s unclear when the override vote will take place. Legislators are in Springfield next week for Illinois State Fair events. Lawmakers, too, are engaged in bipartisan negotiations with the hope that additional legislation will be filed to complement the override in order to gain Republican support.

“We’ve been told to be back on Sunday,” state Sen. Heather Steans, D-Chicago, said.

The Senate has until Aug. 16 to try for the override. Rauner issued his amendatory veto on Aug. 1.

If the Senate succeeds in overriding the governor’s veto, the Illinois House will then have 15 days to act on it. If the Senate fails to override, they can try again since it is a renewable motion.

School districts across the state would have received a general state aid payment on Thursday, but the school funding bill has held up that payment. Democrats in July tied the release of state funds for schools to the passage of an “evidence-based” school bill in budget bills passed in July. With the impasse over and some money flowing, districts are still expecting payments — the state still owes them for the school year that just ended.

Speaking at a bill signing on Tuesday morning in Chicago, Rauner said he received Illinois State Board of Education numbers on Monday and that his staff was meeting with the board on Tuesday. He urged that the information get out to the public as soon as possible.

“The very, very early preliminary comments I heard last night were consistent with what I have always believed, all districts do at least as well, low income districts do dramatically better and nobody gets worse, which is what the goal of my AV [amendatory veto] was,” Rauner said.

The governor has contended that his veto would put every district on better footing, including Chicago Public Schools.

But the governor’s veto would reduce the amount of money going to CPS under the original bill. Rauner has called the school funding measure a “Chicago bailout” because it would give the district $221 million for teacher pensions while also counting its payments for legacy pension costs. The veto also removed a $200 million block grant CPS receives.

Distribution of the highly anticipated analysis of the amendatory veto was delayed on Tuesday — with the state Board of Education contending that the Illinois Department of Revenue reported a “significant error” regarding tax-increment-financing data.

TIF districts were created to promote economic development in blighted areas with any growth in property taxes going to specific purposes,  such as infrastructure, public improvements and developer subsidies — but not education.

The error could signal a huge discrepancy in the formula. In both the original measure and the veto, the value of property in the district would play a role in how much money school districts get.

The Senate measure offers up a credit to school districts that have access to TIFs — it’s used as part of the formula. But the amendatory veto wipes that out. Critics of the veto contend TIF districts would look wealthier than they actually are. A hold harmless provision would ensure districts don’t lose any money that they already get, but it could mean they’re in line to get less money from an increase in school funding.

Once the incorrect data is updated, it will be sent back to the state board for an analysis. It’s unclear how fast that will take. But the Illinois Senate appeared poised to try to override the veto nonetheless.

Several Senate Democrats on Tuesday said that analysis didn’t make a difference in their quest to override.

“I think the governor’s amendatory veto was the most harmful thing that could happen thus far. So the furtherance of the problem with numbers to model the vast nature of his amendatory veto doesn’t surprise me,” school funding bill sponsor State Sen. Andy Manar, D-Bunker Hill, said. “But we were hoping that the governor’s amendatory veto would be a roadmap to compromise, and it’s been nothing of the sort.”

It’s unclear when the House plans to try for the override. But House Democrats on Monday filed an amendment to a bill with the exact language of the governor’s amendatory veto. They plan to discuss the amendment during a House education committee hearing in Chicago on Wednesday morning.

Steve Brown, spokesman for Illinois House Speaker Michael Madigan, said the House is still determined to override the veto.

“We still think that’s the best plan for funding schools across the state,” Brown said. “There are now several elements that tell us that what the governor has done is worse for schools across the state.”