MADISON, Wis. — Republicans privately negotiated a series of last-minute changes to the Wisconsin budget Tuesday designed to smooth its passage, including removing a cap on a popular tax credit program for disabled veterans and delaying the loosening of requirements for high-capacity wells.

The changes, discussed among Republican legislative leaders in both the Senate and Assembly, were announced throughout the day but never formally introduced. After only 15 minutes of debate on the two-year, $70 billion spending plan, the Assembly quit work for the day so Democrats could be briefed on the Republican changes before resuming Wednesday morning.

"We came ready to debate this bill and we still don't know what's in the bill," Democratic Minority Leader Peter Barca said as his caucus prepared for a briefing with the Legislative Fiscal Bureau. "It seems like it's changing by the minute."

None of the changes Republicans announced got to the heart of the biggest budget issues that have generated the most heat from Democrats and moderate Republicans — namely the growth of private school vouchers statewide and the rejection of federally funded Medicaid expansion.

The budget touches the lives of nearly every person in the state. It would cut income taxes for all tax filers by $650 million over two years, expand statewide private school vouchers currently only available in Milwaukee and Racine, and tighten income eligibility under Medicaid, forcing nearly 90,000 people into federally subsidized exchanges to purchase insurance.

It also would allow for the selling of public properties, freeze tuition at the University of Wisconsin for two years, require DNA to be collected upon arrest for a felony or conviction of any crime, and allow bail bondsmen to operate in the state.

"I am proud of what we're doing," Republican Assembly Speaker Robin Vos said at a news conference before debate started.

Vos said the changes to the plan the Assembly would be voting on were worked out as part of an agreement designed to ensure the budget passes both houses. Clearing the Assembly, where Republicans hold a 60-39 majority, was never in doubt. But in the Senate, where Republicans have a narrow 18-15 edge, moderate Republicans were actively seeking concessions.

One change announced by Vos would delay a provision that would make it easier for big water users to get permits to drill high-capacity wells. Another would remove caps on a property tax credit program benefiting disabled veterans.

A third would give the state Department of Natural Resources the authority to pass an emergency rule restricting public access to land near Lake Superior where protesters have attempted to interfere with preliminary work to open a massive iron ore mine.

But Democrats raised concerns about the changes, including wording that appeared to restrict what information the state Department of Public Instruction could release about voucher school students.

Republican Senate Majority Leader Scott Fitzgerald said he hoped changes being made in the Assembly would satisfy concerns raised by some Senate Republicans and lock up their votes. Sen. Dale Schultz, the most vocal GOP critic, hadn't seen the Assembly changes.

"I have no idea exactly what's in it," he said before the Assembly began debate on the budget. "I imagine whatever's necessary to get the budget passed is in it."

Schultz reiterated his concerns with key parts of the budget, including expansion of the private voucher school program statewide, that were not going to be changed by the Assembly. He declined to say whether he would vote against the plan.

If two or more Republican senators join with Democrats against the budget there won't be enough support for it to pass the Senate.

Moderate Senate Republicans, along with Democrats, had been calling for more changes to the budget, including a scaling back of the voucher expansion and acceptance of the Medicaid money. There were also calls to reject a provision that would kick the Center for Investigative Journalism off of the University of Wisconsin-Madison campus, do away with the DNA collection requirement and not allow bail bondsmen to operate in the state.

But no changes were coming to those parts of the budget in the Assembly, Vos said. He said Assembly leaders have worked in good faith with Republican senators and he hoped the budget would not be changed in the Senate.

Rep. Steve Nass, R-Whitewater, announced on Monday he was voting against the spending plan, in part because it creates a projected $500 million shortfall at the end of the 2015-2017 budget cycle. He and 10 other Assembly Republicans had offered a letter raising objections to various provisions.

"If you are a conservative in Wisconsin and you choose not to vote for this budget, I cannot see a scenario where you would ever vote for a budget," Vos said. The budget gives Republicans 95 percent of what they wanted, and any more than that can't be reasonably expected, he said.

The high capacity wells provision was one of the most controversial items added to the budget by the Joint Finance Committee.

The language would block anyone from challenging high-capacity well applications and permits by arguing the state Department of Natural Resources didn't consider the cumulative impact of the well and surrounding wells on the environment.

But the Assembly planned to delay the change until July 1, 2014. Vos said it was his hope that the Legislature would revisit the issue before then.

High-capacity wells have long been a contentious issue in Wisconsin. They've come to the forefront again in recent years with the growth of businesses that use vast amounts of water, such as sand mining and factory farms.

The budget committee also voted to include a cap on a growing property tax credit program for veterans.

The committee placed a $2,500 limit on the amount of property taxes that could be reimbursed to veterans who are fully disabled. The committee also created a mechanism to drop higher-income veterans and their spouses from the program.

Gov. Scott Walker had called on the Legislature to fix the issue after veterans groups called it shameful and said the budget was being balanced on the backs of veterans.