COLORADO SPRINGS — In a nondescript office building on the north side of this conservative enclave, more than a dozen volunteers spent hours making calls to educate voters about a new initiative that will allow parents to use taxpayer dollars to send children to private schools.

At the same time, just miles down the road, the political network behind the effort gathered hundreds of its wealthiest donors at a posh mountainside resort to raise money to support the campaign to remake the education system.

The confluence of policy and politics epitomized how the conservative billionaires Charles and David Koch flex their organization’s muscle and spread an ideological agenda in states across the nation.

“The value of this network cannot be overstated,” said Stacy Hock, a Koch donor and conservative education advocate in Texas. “The ability to stand on the shoulders of the giant that is this network to make yourself more impactful and strategic changes the game.”

The phone calls to middle-of-the-road voters and presentation to donors in Colorado last week were part of the Koch network’s six-figure campaign to promote school choice and education savings accounts, or ESAs.

The effort in Colorado involves the Americans for Prosperity Foundation and the Libre Initiative, a group focused on Hispanic community outreach. Together the organizations are making calls and sending flyers to voters this summer, two of which promote ESAs as a way to “give families the freedom to select schools, classes and services that fit the unique needs of their kids.”

Five states currently offer the accounts as a school-choice option, according to the bipartisan Denver-based National Conference of State Legislatures. The program allows parents to use taxpayer dollars for private school tuition, online learning programs, books or tutoring. And Colorado, which doesn’t yet offer ESAs, is one of five states where the Koch network is looking to expand or establish the program through legislation or a ballot measure.

Arizona Gov. Doug Ducey touted the ESA program he helped establish during a session at the three-day Koch donor retreat at the Broadmoor. “These type of innovations are making a huge difference,” he said. But, he added, to make it happen, “I needed the power of the network.”

In Arizona and other states, the accounts are controversial. The Colorado Education Association, the state’s largest teachers union, considers them an attack on public schools.

“What ESAs are designed to do is divert public money into private schools,” said CEA president Kerrie Dallman. “When they do that, it undermines the principles of equity and accountability while doing nothing to increase the quality of education.”

Great Education Colorado, an advocacy group, echoed the sentiment in a 2016 letter to lawmakers in which it asked them to “ensure that the all-too-scarce public dollars allocated to K-12 education are only used for public schools.”

“It just doesn’t make sense to me,” organization director Lisa Weil said of the idea of ESAs. “The public dollars that we have are critical, they are scarce, they are valuable to make sure we provide the resources that every kid needs to succeed.”

The supporters of the existing system in Colorado compare ESAs to school vouchers, but the programs often have different parameters. In a typical voucher program, the state sends taxpayer dollars to private schools for the cost to educate a student. The money in the education savings accounts would go to the parent, who can use the money for private school tuition and other education services for a child.

The Koch network considers Colorado an attractive state for its message because public charter schools are a bipartisan cause. In the 2017 session, lawmakers equalized funding for charter schools with district schools.

EdChoice, a conservative education advocacy organization aligned with the Kochs, commissioned a survey in 2015 to introduce Colorado to the ESA issue, finding strong support when cast in favorable terms.

The summertime effort in a nonelection year demonstrates the Koch network’s permanent apparatus in Colorado and how it can mobilize like-minded volunteers into action.

“When there’s not an election, there’s not a lot of noise and you can have a lot of impact,” said Michael Fields, the senior director for issue education at the national Americans for Prosperity Foundation.

The ESA model is relatively novel in Colorado, and Fields sees his team’s work as a “race to who defines the issue first.”

How the program would work in Colorado remains to be seen.

In Arizona, a model state, the program started with limited eligibility for students with learning disabilities and then expanded to include those at schools with poor performance and other students. Earlier this year, the state expanded the program to more students. The amount of money parents receive is also different but typically benchmarked to the per-pupil public education cost.

If the persuasion effort is successful in Colorado, the Koch network’s political groups could push it forward as soon as the 2018 legislative session or possibly onto the ballot for voter approval.

Fields is optimistic: “I think we can get something across in the next few years.”