Voters emphatically rejected a $950 million tax increase and the school funding revamp that came with it, handing Amendment 66 a resounding defeat Tuesday night.

The measure fell behind by a large margin as the early returns were counted, with nearly two-thirds of voters giving it a thumbs-down, and the outcome was clear just a little more than an hour after the polls closed.

“Colorado families spoke loud and clear,” said Kelly Maher, executive director of Compass Colorado, which opposed Amendment 66. “We need substantive outcome-driven reforms to the educational system before we ask families and small businesses to foot a major tax bill.”

The big-ticket item on the statewide ballot would have injected new tax dollars into K-12 education, but to do so it proposed changing the state income tax from a flat rate of 4.63 percent to a two-tiered arrangement.

The new revenue stream would have been aimed at several areas, including preschool, full-day kindergarten, additional support for English-language learners, and locally determined innovations such as longer school days and years.

It also promised greater funding for charter schools and support for previously passed reforms such as the educator effectiveness framework that went into effect this school year.

The amendment represented the first major overhaul to school finance in nearly two decades, crafted over more than two years by a consortium of interests and carried into the political arena primarily by Sen. Mike Johnston, the Denver Democrat who had earlier success achieving bipartisan education reform.

He touted the measure as one that would bring equity in education to students across Colorado. The new system sought to change the school funding mechanism by resetting state and local shares based on factors like median income.

“Tonight, we know that goal isn’t happening as soon as we’d like,” Johnston said. “But it will happen.”

He added that both sides agree on what’s best for kids and schools.

“What we disagreed about was on how to pay for them, and that was the narrow question that was decided tonight,” he said. “It will take now a renewed commitment to start that conversation again, but we know now that a great deal rides on it.”

Gov. John Hickenlooper risked considerable political capital to support Amendment 66, whose passage he said would constitute “the most comprehensive education-reform initiative in the history of the United States.”

“For some people, Amendment 66 was only about taxes,” Hickenlooper said after conceding defeat. “For others, it was about investing in and sacrificing for our most valuable resource: our children. We are committed to common-sense solutions and remain committed to collaborating with everyone to make Colorado’s education system the best it can be.”

Critics seized on what they called insufficient reform and accountability as well as the inequity of a tiered tax structure and its implementation while the Colorado economy remains fragile amid a slow recovery from the recession.

Dustin Zvonek, the state director for Americans for Prosperity, hailed the voters’ decision.

“We congratulate Coloradans for having the common sense to reject this unnecessary and unjustified tax grab,” he said. “Passing Amendment 66 would have gravely wounded the state’s economy and business climate, while rewarding a reform-resistant education system with an unearned windfall.”

The rejection of the tax hike and school-finance overhaul came despite proponents’ huge war chest — more than $10 million — for a campaign to convince voters that a tax hike to bolster education constituted a worthwhile investment.

But this effort faced a formidable challenge.

Johnston’s Senate Bill 213, which reconfigured the way the state would distribute education dollars to its 178 districts, made its way through the legislature without Republican support.

Although it passed and was signed by the governor, SB 213 would go into effect only if voters approve a finance mechanism before November 2017.

Election watchers predicted that proponents faced the uphill battle in making their case for such a sweeping — and expensive — change. The last proposed statewide tax increase for education, Proposition 103 in 2011, also lost by a large margin.

Business interests were split on Amendment 66, and some organizations, including the Denver Metro Chamber of Commerce, simply chose to remain on the sidelines .

The race attracted national attention, including support from U.S. Secretary of Education Arne Duncan, and op-eds in The New York Times and The Wall Street Journal weighing in pro and con, respectively.

National money also entered the campaign in a big way, with millions from the National Education Association and late donations from New York Mayor Michael Bloomberg and philanthropists Bill and Melinda Gates supporting the measure.

Final campaign-finance reports won’t be out until Dec. 5.

That money gave proponents a huge edge in spending on television advertising. Opponents relied on a much smaller TV presence financed by an arm of the Independence Institute, which raised about $734,000 for “educational outreach.”

But ultimately, the state’s electorate passed judgment.

“Having spent the last eight months arguing that this particular bill was not the right path for Coloradans, tonight’s result does not mean education reform is dead in Colorado,” said state Treasurer Walker Stapleton, an outspoken opponent of Amendment 66. “We will go back to the drawing board to reform our vitally important public education system the right way.”

Kevin Simpson: 303-954-1739, ksimpson@denverpost.com or twitter.com/ksimpsondp

Staff writer Josie Klemaier contributed to this report.

Amendment 66

Yes34%

No66%

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