Some low-income families unhappy with their public schools would get help paying private school tuition under a plan that won tentative approval in the Texas Senate on Monday.

Senate Bill 4, which would use state tax credits to entice up to $100 million in business donations to fund a scholarship program, cleared the chamber 18 to 12 with two Republicans, Konni Burton of Colleyville and Robert Nichols of Jacksonville, breaking party lines to vote against the measure. One Democrat, Eddie Lucio of Brownsville, voted in favor.

Before it passed, Democrats raised concerns about the plan, arguing that it diverted money that should be going to public education into an unaccountable private school system. “They don’t have the same kinds of requirements that our public schools do,” said state Sen. José Rodríguez, D-El Paso. “I can’t seem to get around that.”

While defending his proposal, state Sen. Larry Taylor, R-Friendswood, insisted that the legislation should not be considered a private school voucher program — a notion that has proved politically toxic in the Legislature.

“I don’t think we are taking money from the public schools. The student is leaving,” said Taylor, who chairs the Senate Education Committee. “This is private money — not state money — that is donated.”

Sen. José Menéndez, D-San Antonio, said he viewed the legislation as a way to “short-circuit around the whole voucher concept.”

“It is money that a corporation will be giving to a scholarship program in lieu of paying tax,” he said.

Sen. Rodney Ellis, D-Houston, called on Taylor to add language banning private schools participating in the program from using Common Core, the national set of curriculum standards that Texas lawmakers prohibited in the state’s public education system in 2013.

"It just defies logic that you would apply a different standard to private schools using taxpayer subsidized money,” said Ellis, after his amendment was tabled at Taylor's urging.

Lt. Gov. Dan Patrick has vowed to use his office to move voucher or so-called school choice legislation, which he argues would offer an essential lifeline for students at low-performing schools whose families can't move to a better neighborhood.

"Since I joined the Texas Senate in 2007, I have pushed for a strong school choice bill to pass the Senate," Patrick said in a statement released after the vote. "This is the first time a bill of this caliber has ever made it out of the Texas Senate, and now an estimated 15,000 students will have more choice."

Taylor’s measure offers a more limited vision for the program than lawmakers initially proposed.

It would set up an initial $100 million in state tax credits for businesses that donate money to fund scholarships for special-needs and low-income students. The scholarship program would exclude sparsely populated areas, a concession perhaps crafted to earn the support of rural lawmakers who have been reluctant to approve such a program in the past.

Distributed through nonprofit foundations approved by the state, the scholarships would be capped at 75 percent of the average state funding per student, which currently comes to just over $6,000.

Only students who qualify as special needs or whose parents make annual salaries within 250 percent of the federal poverty limit and who currently attend a public school with an enrollment of more than 100 in counties of more than 50,000 people would be able to apply.

To enroll a tax credit scholarship student, private schools would have to be accredited and annually administer a nationally recognized standardized exam.

After a final vote in the Senate, the legislation will proceed to the House, where its fate may depend on whether lawmakers believe the accreditation requirement offers enough accountability.

House Public Education Chairman Jimmie Don Aycock, R-Killeen, whose panel would have to approve the bill before it reaches the floor, has said that for lawmakers in the lower chamber to even start a conversation about providing state support to private schools, it would have to be assured of adequate quality control.

“The House has always been more reluctant … about spending public dollars on nonpublic entities,” he said at a Texas Tribune event in January. “As long as there is state money involved, I want some accountability in how that is going to be spent.”