“Dark money” groups have begun filling their war chests as they prepare for battle over Gov. Jared Polis’ proposal to offer property tax relief by diverting money away from a popular tax refund program.

The most recent campaign finance filings with the Secretary of State shows nearly $1.9 million has been raised on both sides of the question known as Proposition HH.

But more than $1.5 million of that comes from nonprofits and other organizations that don’t identify their funders, a practice known in political circles as “dark money” spending.

Such groups — often politically active nonprofits — are legally allowed to spend money on electioneering activities without having to disclose their funders; hence, the “dark money” label. Both progressive and conservative entities have increasingly turned to dark money spending over the last numbers of years.

The question, referred to the ballot by majority Democrats in the General Assembly, will ask voters this November for permission to raise the Referendum C cap — the state’s annual revenue limit — by 1% and keep that additional revenue for a 10-year period. In 202425, $128 million would be transferred from the general fund to reimburse local governments for lost property tax revenue, plus $150 million to the state education fund, according to the General Assembly’s Blue Book.

The amount headed to the state education fund, which helps pay for K-12 education, is expected to increase every year, with $270 million in state budget year 2025-26.

In future years, the extra amount the state can spend is expected to grow, reaching $2.2 billion by 2032, according to state estimates.

A companion measure, contained in House Bill 1311, will provide an equalized Taxpayer’s Bill of Rights refund to taxpayers, should Proposition HH pass, giving each single filer $873 next year, or $1,746 for joint filers, based on recent projections from the governor’s Office of State Planning and Budgeting.

If approved by voters, Proposition HH would also make a temporary assessment rate reduction for residential property classes and reduce valuations — and the property taxes tied to those valuations — for owner-occupied, senior and multi-family housing by $50,000 in 2023, and by $40,000 from 2024 to 2032.

If voters rejected the measure, the TABOR refund in 2024 would be based on the state’s current six-tier refund mechanism, which is decided by income levels.

Critics have said that by increasing the Ref C cap by 1% each year for the next nine years, that compounds the amount the government is allowed to keep and spend on property tax relief and state education funding, reducing or even eliminating TABOR refunds.

Campaign finance data through Aug. 30 show critics lead supporters of the measure by about $409,000.

The largest fundraising to date is for No on HH, backed by Advance Colorado Action and Defend Colorado. The latter has been supporting conservative causes for the last several years. Both groups don’t disclose their funders.

The two groups have so far kicked in $500,000 each to the No on HH committee.

Four other groups oppose Proposition HH, although none is as well-funded as the No on HH committee.

Among the groups is Americans for Prosperity Colorado Issue Committee, which spent just shy of $100,000, all of it in-kind contributions, such as canvassing, doorhangers and other forms of advertising, and all paid for by the organization’s Virginia headquarters. The group, which is tied to the Koch brothers, also does not disclose its funders.

Taxpayers for a Better Deal, which is backed by the Independence Institute, spent $3,500 in non-monetary activities. The Independence Institute also does not disclose funders.

Two groups with ties to TABOR author Douglas Bruce also oppose Proposition HH. The largest contribution to the TABOR Coalition of $500 comes from the TABOR Foundation’s TABOR Committee, which is led by former state Rep. Penn Pfiffner.

Bruce is in charge of HH-No.com, which has yet to report any contributions.

Bruce, considered the father of the Taxpayer’s Bill of Rights ballot measure that voters approved in 1992, served one term in the state House, which included a censure by the House for kicking a Rocky Mountain News photographer. He was convicted of felony tax evasion in 2012, violated the terms of his probation and eventually served two years in prison.

Only one group is fundraising to support Proposition HH: Property Tax Relief Now.

The group, too, has its own list of dark money funders.

The list includes Education Reform Now Advocacy of New York, which is tied to Democrats for Education Reform, started by New York hedge fund managers and which opposes teachers unions and supports charter schools.

The National Education Association and the Colorado Education Association both have contributed $100,000. The Sixteen Thirty Fund, a New Yorkbased group that has contributed millions to Democratic causes in Colorado, has so far given $60,000.

Boldly Forward, which was started to back the gubernatorial campaign of Gov. Jared Polis and which also does not disclose its donors, has contributed $50,000. The group shifted to advocacy for Polis’ agenda in 2020.

The largest donation to date to the pro-HH committee is $250,000 from Gary Advocacy, which is part of Gary Community Ventures. The latter was led by Mike Johnston until he successfully ran for Denver mayor. The nonprofit got its initial funding from Denver oilman Sam Gary of Gary Energy.

Gary Community Ventures was the major funder of 2021’s Proposition 119, which increased marijuana taxes to pay for out-of-school activities, and Amendment B in 2020, which repealed the Gallagher Amendment. Colorado voters in 1982 approved the Gallagher Amendment, which tied property tax revenue from residential assessed value at 45% of the statewide total. Supporters said the effect is to effectively keep property tax low.