Critics argue that increasing taxes while the state's economy wrestles with recovery is a bad idea and that most of the money won't trickle down to teachers and students. It will be eaten up at administrative levels and fund PERA, while leaving the door open for future tax increases.
What's more, there are no guarantees, opponents argue.
Studies show the initiative could both help and hurt the state's economy.
It all depends on who you talk to.
At this stage in the battle for votes, with the Nov. 5 election nearing, there's passion on both sides. Spin is everything and if you don't understand it all, you're not alone.
"The obvious thing that is shaping the debate is that it will require a tax increase," said Josh Dunn, associate professor of political science at the University of Colorado at Colorado Springs. "I think that's drowning out everything else."
"It's difficult to gauge the public's position right now, what the voters think," said Dunn, whose specialty is education policy and school finance.
At a taxpayer cost of $950 million, Amendment 66 would trigger a revamp of school financing in Colorado. To pay for it, a typical household in the state would fork over $133 a year, proponents estimate.
It's the funding trigger for implementation of SB213, which overhauls how state taxes would be used to fund public education.
Amendment 66 makes plenty of promises about impacting public education from pre-school through the 12th grade.
Not everybody believes the promises, however, and big money is rolling in as both sides rush to get their messages out.
On Monday, Colorado Treasurer Walker Stapleton and Independence Institute President Jon Caldara spoke to business people at a meeting at The Broadmoor. Both oppose the initiative. Four days later, the El Pomar Foundation held a debate between supporter Sen. Michael Johnston, D-Denver and Caldara.
Both sides are loaded with heavy hitters, although the biggest war chest - about $7 million - belongs to supporters.
Among those who have endorsed Amendment 66 are Colorado Commits to Kids, National Education Association, Colorado Education Association, Greater Education Colorado, Colorado College President Jill Tiefenthaler, The Bell Policy Center, and the League of Women Voters of Colorado.
"We think it's good for Colorado," said Rich Jones, director of policy for the Denver-based Bell Policy Center. "It's good for the students and for the families. It's wide-ranging and has a lot of very positive things for education."
Against it: Independence Institute, the Colorado arm of the National Federation of Independent Business, Americans for Tax Reform, activist and former state lawmaker Douglas Bruce, and the South Metro Denver Chamber.
The Douglas County School Board unanimously passed a resolution on Oct. 1 opposing Amendment 66, arguing that the county's taxpayers would pay $90 million to $100 million for a return to Douglas County schools of about $50 million.
"We favor a system where dollars follow a student based on their needs and we don't really feel like Amendment 66 would do that adequately," said board member Meghann Silverthorn.
"We're OK with helping other districts and other areas who might not have resources, but we want to know our tax money is going to something that provides better outcomes for students and there's no guarantee for that."
Douglas County also would be faced with using a significant portion of its revenue to pay for full-day kindergarten classes. The county does not have funds or facilities for that now, Silverthorn said.
"There are strings attached," she said. "It's like telling a kid, we're going to give you more allowance, but we're going to tell you how to spend it."
Other school boards, however, support the initiative, including Alamosa School District RE-11J, Aurora Public Schools, Boulder Valley School District and Brighton School District 27J,
Then there's the question of $1.1 billion in extra cash for fiscal 2013-2014 the state received that could have been spent on K-12, but was diverted by the Democrat-controlled state Legislature to other projects and parked as reserve funds. (For more, go to http://gazette.com/flush-with-cash-colorado-officials-back-tax-hike/article/1503472.)
Nobody necessarily quarrels with the need to continue to improve education.
Colorado has seen improvement the past few years in test scores, the rate of graduation and enrollment in college, according to the Colorado Department of Education.
But among developed nations, the United States is at best average, at 17th in the world for education, according to Pearson, an education company. South Korea was at the top.
A report by Harvard's Taubman Center for State and Local Government in 2010 found that only 6 percent of the students in the United States performed at an advanced level in mathematics, lower than 30 other countries. And while students are making gains, the "gains within the United States have been middling, not stellar," according to a Harvard report measuring progress by lagging countries toward closing an international education gap.
"While 24 countries trail the U.S. rate of improvement, another 24 countries appear to be improving at a faster rate. Nor is U.S. progress sufficiently rapid to allow it to catch up with the leaders of the industrialized world," the report says.
Said a task force report by the Council on Foreign Relations in 2012: "Overall, U.S. educational outcomes are unacceptably low."
There are myriad theories behind education's failure in one of the world's most powerful countries. Not the least of them has been funding cuts among states hammered by the ailing economy.
According to a report by the Center on Budget and Policy Priorities, states provide less per-pupil funding for kindergarten through 12th grade than they did six years ago.
The report says that at least 34 states are providing less funding for the 2013-2014 school year than they did before the recession of 2007-2009.
Where funding has increased, it doesn't come close to making up previous shortfalls. In New Mexico, for instance, an increase in school funding of $72 per pupil falls considerably short of the state's $946 per pupil cut over the past five years.
But lack of funds alone can't be blamed for all the nation's education shortfalls.
Indeed, according to Chester Finn Jr., president of the Washington, D.C.-based Thomas B. Fordham Institute, there's a thing called culture that has significant relevancy.
By the time students are 18, he says in the Pearson report, they will have spent 9 percent of their lives in school if they had perfect attendance. That leaves 91 percent of their lives outside school.
"If the 91 percent is cooperating with the 9 percent, then you have a good recipe. If there is no positive re-enforcement of educational achievement taking place outside the school - if, for example, the larger culture glorifies celebrities who can barely read - you will have huge trouble."
While Coloradans aren't always averse to upping taxes, education funding hasn't fared well.
In 2011, voters overwhelmingly rejected Proposition 103, which would have raised the state's income-tax rate from 4.63 percent to 5 percent and sales tax from 2.9 percent to 3 percent for five years to fund education. The measures would have generated roughly $2.9 billion over five years for K-12 and public colleges and universities.
"It's a tax increase, and this is Colorado, home of TABOR, " Dunn said.
Proponents, however, are optimistic.
"I think there is a lot of support out there for it," said Bell's Jones. "There's an awful lot of work being done to reach out to people and reach out to families. I think it will pass, but I think it will be close."
Jones acknowledges, however, that it's a tax hike, "which in any circumstance is always a challenge, but I think this one benefits from the fact that it is very clear in the legislation and the amendment what it's going to be used for and where it will go. It's for something that I think has a lot of support throughout Colorado."
It's a matter of educating voters, says Curtis Hubbard, spokesman for Yes on 66.
"What we find is that in talking to voters, when we're able to explain how Amendment 66 can deliver smaller classes, more one-on-one, retention, restoration of programs like gym and art and music and deliver reforms that would make Colorado a national leader in education, they are supportive of it," he said.
A point of contention between the forces is how the amendment will affect the economy.
A study released Oct. 9 by the University of Colorado's Leeds School of Business says the amendment "will slow economic growth, reduce personal income and cut private-sector jobs."
The economy would lose $224 million in economic activity during the first five years, according to the study.
A second study by the school, however, found that if approved, Amendment 66 could produce about $4 billion in annual economic gains once the factors of a reduced dropout rate and increased graduation rates are included.
Yet another study, this one by a professor at the Daniels College of Business at the University of Denver found that Colorado stood to gain $3.3 billion a year in economic impact when other factors were considered, such as lower unemployment and less welfare, less crime and savings in health care and increased retention of businesses and recruitment. Still, 96 percent of the 7,500 members of the Colorado chapter of the National Federation of Independent Businesses said they oppose the amendment in a recent survey.
"I think right now small businesses don't believe this is the best time to be raising taxes in general," said Tony Gagliardi, Colorado director. "Plus, it is poorly written."
Gagliardi said it could "create an end run around TABOR for future taxes."
"I think the question is, why do you not see bipartisan support for it?" he asked. "They've gone as far as to say businesses support it. We say, show us the businesses. I've never had an issue come back with that type of opposition."
Supporters argue that better education would translate into a more educated workforce, which would help the economy.
"We don't think over the short run it will hurt the economy," Jones said. "The money is being spent in Colorado schools and on textbooks, that money is going to stay in the Colorado economy. We don't see it being negative in that way, but also it is the type of investment we have to make to be competitive in the long run."
In the end, there are two options and voters on Nov. 5 will make that decision.
Pass it or live with the status quo, says Johnston, the face of the amendment.
The tax, he said, "is an impact, but it's an impact in exchange for things like full-day kindergarten, early childhood intervention, more supplies, construction, getting back the thousand teachers we lost, all of the things that we know are huge returns on investment."
Amendment 66, he said, also would get rid of Amendment 23, which calls for increases every year in K-12 based on inflation.
During the debate Friday, Caldara called Amendment 66 a "pig in a poke."
"There's not a single guarantee where this goes," he said.
And if the initiative fails this time around, supporters can bring it back to voters.
"They have five years," Caldara said. "This is not going away."
Analyst Dunn has his doubts.
"I remain skeptical," he said. "I'm skeptical that the reforms will actually have any teeth and that they will actually come to fruition."
If Amendment 66 passes, he said, "It will be by a narrow margin. But I could also see it going down by a very wide margin."