Gov. Bruce Rauner on Monday issued an amendatory veto of legislation needed to implement a historic school funding bill, sending it back to lawmakers to “be cleaned up” to allow students attending three dozen private schools to more quickly take advantage of a new tax-credit scholarship program.

The veto prompted a key sponsor of the school funding measure — aimed at doling out more money to the state’s neediest school districts — to accuse the governor of creating “absolute chaos.”

Left unknown are any potential delays Rauner’s action could cause to the state implementing the new school funding formula. The Illinois State Board of Education had been prepared to launch a system of distributing dollars by March, supporters of the school funding measure said on Monday.

The governor’s office, however, said it was “unfair” for “critics” to say Rauner’s amendatory veto would delay implementation of the school funding measure. And a spokeswoman said the state is “several months” away from implementing the formula, meaning there’s still time to make the changes the governor is seeking.

It’s the latest chapter in a years-long struggle to change the way the state distributes money to public schools — a fight that escalated last August when Rauner vetoed a school funding measure. Lawmakers approved a compromise measure weeks later, which included the scholarship program heralded by Cardinal Blase Cupich, but decried by the Chicago Teacher Union.

And the governor’s campaign last year cited the school funding measure as his top accomplishment.

In the amendatory veto of a Senate trailer bill passed in November, the governor argues that the bill, which offers tax-credit scholarships to low-income students attending private schools, is unfairly limited to schools “recognized” by the Illinois State Board of Education, rather than any school “registered” with the board.

“While it is prudent to require compliance with ISBE measures that protect the health, safety and well-being of students, the current timelines to become recognized will exclude at least 36 schools that are still in the process of registering for and moving toward recognition,” the governor argued in his amendatory veto message. “The ramifications of this initial exclusion could potentially last for two years.

“The students attending or looking to attend these schools deserve the same access to Invest in Kids scholarships as those in already recognized schools. Their educational opportunities cannot wait for years.”

In a separate news release, the governor said the “defect” in the bill that passed would exclude 36 Catholic and other private schools, “many of which serve African-American communities” from taking advantage of the scholarship program.

“Inclusivity was the spirit of this legislation to begin with, and we simply must ensure that we follow through with the appropriate language to get the job done.”

Meanwhile, the governor’s office said the state Board of Education is still working on the new funding formula and tier funding is still “several months” from being sent out.

“It is unfair for critics to say that this amendatory veto will delay implementation of SB 1947,” Rauner spokeswoman Rachel Bold said in a statement.

State Sen. Andy Manar, D-Bunker Hill, called the amendatory veto Rauner’s version of tossing “his own request in the trash.”

“Here’s what Gov. Rauner accomplished today: absolute chaos while undoing all of the equity components in the school funding reform legislation that he takes credit for passing,” Manar said in a statement. “I am perplexed and puzzled by the motivations of this governor who claims to care deeply about public education in Illinois. “Why would he veto a bill that he sought in the first place?”

Senate Democrats said the bill was intended as a form of “technical cleanup,” which had been requested by the governor’s administration.

The Illinois Senate returns to session on Jan. 30. Lawmakers can accept the changes, reject them with an override or choose not to take up the veto, which would kill the measure.