Billionaire industrialist Charles Koch has steadfastly refused to support GOP presidential nominee Donald Trump. (Patrick T. Fallon for The Washington Post)

COLORADO SPRINGS — The Koch political network, which has steadfastly refused to engage in the 2016 presidential contest, plans to invoke Democratic presidential nominee Hillary Clinton in paid messages to voters as part of its campaigns supporting GOP Senate candidates, top officials said Saturday.

“We are going to tie the Democrat candidates to Hillary Clinton and the failed policies that she supports, and highlight the differences with the Republican candidates that we favor and that we’re supporting,” said Mark Holden, chairman of the board of Freedom Partners Chamber of Commerce, the network’s funding arm.

In Ohio, for example, Koch-backed groups may hit Democratic Senate contender and former Ohio governor Ted Strickland on his energy stance, comparing his position to that of Clinton's.

Charles and David Koch have historically been hated by Democrats and loved by Republicans. But regardless of which party you support, there's almost no question that the Koch brothers have made money off of you. (Jeff Simon,Daron Taylor/The Washington Post)

But Holden said the network has no plans to run an explicit campaign opposing Clinton’s efforts to reach the White House, saying: “We are going to differentiate on policies alone. It’s not going to be anti-Hillary.”

The plans to invoke Clinton in Senate ads come as the network is under pressure from some of its wealthy donors to get off the sidelines and use its national field infrastructure and paid advertising capacity to back GOP presidential nominee Donald Trump. But Koch Industries chief executive Charles Koch has refused to budge, repeatedly expressing his dismay with Trump's tone and policy positions.

Still, the invocation of Clinton in Koch-backed ads is another way that the operation could end up indirectly boosting Trump. Koch-backed groups have hundreds of staffers in the field, gathering reams of information on voters in key battleground states that filter back to the Republican National Committee and GOP candidates through a data-sharing agreement. And the network’s permanent ground force, which far outstrips Trump’s field operation, could help propel Republicans to the polls in key states such as Ohio, Pennsylvania, Wisconsin, Nevada and Florida.

Holden told reporters Saturday that the network will not jump into the presidential race, even after Trump’s choice of Indiana Gov. Mike Pence (R), a Koch favorite, as his running mate.

“We’re focused on the Senate,” he said. “It gets back to what we look at to engage in any electoral contest. We have to have an aligned candidate from a values and beliefs and policy perspective. And then we need to look at what the candidate’s doing: Are they talking about the issues that we believe need to be talked about in a positive, productive way? Are they running a good campaign?”

Moments before Holden addressed reporters, Trump — who had been in Colorado Springs for a rally Friday — tweeted that he had rejected a sit-down with the billionaire conservative brothers.

“I turned down a meeting with Charles and David Koch,” he wrote. “Much better for them to meet with the puppets of politics, they will do much better!”

But Holden said he was not aware of any discussions with Trump’s campaign about a possible meeting. “You will have to talk to him about what his facts are and what he’s relying on,” he said.

About 400 conservative donors were scheduled to participate in this weekend’s semiannual meeting of the Koch network, held in a majestic Italianate resort nestled at the base of the Rocky Mountains. The theme of the gathering, which will include policy and political briefings, is a Brighter Future: Reversing America’s Decline, Opening Opportunity for All.

A number of top Republican elected officials are set to attend, including House Speaker Paul D. Ryan (R-Wis.); Sens. John Cornyn (Tex.), Cory Gardner (Colo.), Mike Lee (Utah) and Tim Scott (S.C.); Reps. Jason Chaffetz (Utah), Mike Coffman (Colo.) and Mike Pompeo of (Kan.); and Govs. Matt Bevin of Kentucky, Doug Ducey of Arizona and Scott Walker of Wisconsin.

The Washington Post and other news outlets were invited to cover portions of the weekend gathering on the condition that they do not name donors in attendance without their permission.

After originally planning to spend $889 million in the 2016 cycle, the Koch operation is now on track to invest $750 million, with about one-third — $250 million — financing the policy and political campaigns of groups such as Americans for Prosperity, Freedom Partners Action Fund, Concerned Veterans for America and the Libre Initiative and Generation Opportunity, officials said.