Proponents and opponents of a $950 million tax increase for schools have kicked their campaigns into high gear, hoping to educate voters before the November election day bell rings.

As voters begin to receive their ballots in the mail, proponents have been using nearly $8 million to pump out television and radio advertising, among other expenditures.

Meanwhile, thinly strapped opponents are distributing press releases and participating in debates to debunk claims by proponents that the initiative would send money directly into the classroom.

Voters are asked to create a two-tier state income tax rate. Taxpayers earning up to $75,000 per year would see their rate increase from 4.63 percent to 5 percent; and earners above $75,000 would be taxed at 5.9 percent.

Based on the median household income in Colorado of $57,000, taxpayers would see their annual income tax increase by about $133.

The initiative stems from Senate Bill 213 this year, in which the Democratic-controlled legislature rewrote the School Finance Act. The law calls for all-day kindergarten, reforms to enrollment funding, more money for at-risk students and English language learners, measurements of academic growth and achievement, spending transparency and equitable funding for all public schools – including charters.

Opponents this week also highlighted lackluster support from the business community, including opposition from Colorado Concern, a group of Colorado business executives.

Colorado Concern joined the South Metro Chamber of Commerce in expressing opposition from the business community. Other notable opponents include rural associations such as Club 20, Progressive 15 and Action 22.

Colorado Concern fears over shifting to a tiered tax rate. The organization is also concerned that the Colorado Education Association, which has donated $2 million to Amendment 66, has threatened to sue over SB 191. Many of the reforms in SB 191 would be funded by the revenue raised through Amendment 66.

“To us, asking for nearly $1 billion annually on the one hand — as CEA is doing as a proponent of Amendment 66 — when you plan to file a lawsuit over components of the very measure you are seeking to fund, felt disingenuous at best,” said Tamra Ward, president and chief executive of Colorado Concern.

“Voters will decide the outcome of Amendment 66, as they should,” Ward continued. “Our goal in this exercise was simply to shine the light of day on actions we believe were less than transparent, ensuring our fellow Coloradans were provided with all the relevant facts as they cast their ballot.”

But Amendment 66 proponents highlight endorsements from the Greeley Chamber of Commerce, Hispanic Chamber of Commerce of Metro Denver, the Public Education and Business Coalition, Colorado Black Chamber of Commerce, Colorado Women’s Chamber of Commerce and the Boulder Chamber, among other business groups.

Curtis Hubbard, spokesman for Amendment 66, said the initiative has a unique coalition. “We have more than 135 CEOs and business leaders signed on; we are at or just surpassed 400 total endorsements; we have education reformers, the teachers’ unions that are not normally aligned; we have the health care community; we have the higher education community; we have school boards; we have chambers of commerce — so we have a big coalition,” says Hubbard. “It may not be the traditional coalition, but that’s because there’s never been a ballot issue like Amendment 66.”