Backers branded those opposing vouchers for private schools "bigots," and accused them of spreading lies.
The opponents countered that the program, which offers vouchers of $500 to $3,000 depending on income, would be a subsidy for the wealthy and unconstitutionally pump tax money into private and religious schools.
Earlier Tuesday, Congressman Jim Matheson was the latest office holder to speak out against vouchers.
"It's a bad idea to use public money to spend on private academies," said Matheson, a Democrat.
Guaranteed public education is one of the great traditions of America and Utah, he said. "As we now face the challenges of the global economy, this is not the time to be taking resources from the public education system."
The most recent poll on the issue, by the Center for the Study of Elections and Democracy at Brigham Young University, found 61 percent of Utah voters oppose vouchers.
At the debate, Alan Smith, a lawyer for the anti-voucher Utahns for Public Schools, belittled the program as flawed, describing a hypothetical private school called "Professor Harold Hill's Think Method School of Government and Civics." His school legally would accept vouchers - offering parents a $1,000 kickback - though only offering three class meetings a year in a public park. The students would simultaneously continue their education in public schools. "My school is perfectly kosher under the bill," Smith said.
Patrick Byrne, chief executive of Overstock.com, countered that Smith's hypothetical case was "snickering and half truths."
"It assumes that parents would take a kickback over educating their child," Byrne said.
The law's sponsor, Rep. Greg Hughes, R-Draper, said the bill will offer low-income families education options.
The Utah Education Association's Vik Arnold asked why, then, is the program not limited to low-income families?
"It's available to everyone. It's available to the governor. It's available to millionaires - whether you need financial aid or not."
Smith said the program lacks accountability "You don't have a say how your money is spent. Your political choice is taken away."
But Byrne said the vouchers simply shift control from the educational bureaucracy to parents. "It's not about accountability. it's about bigotry," he said.
Arnold countered: "It is the private schools that choose to accept students or not. That is where there is bigotry - if indeed there is bigotry, Sir."