As the son of Mexican migrant workers and a veteran of the George W. Bush Administration, Daniel Garza has been frustrated by President Donald Trump’s hard-line approach to immigration.

To push back on it, he’s revving up a grassroots effort to lobby Congress, backed by the billion brothers Charles and, until recently, David Koch.

As head of the conservative mega-donors’ LIBRE Initiative aimed at Hispanics, Garza will be organizing five public rallies in the next week aimed at shaking loose a congressional stalemate on immigration, highlighting yet another looming deadline for courts to decide how to handle children who came to the country illegally.

“It’s been exhausting. It’s been frustrating. But there’s too much at stake just to give up and walk away. There are lives that are impacted by this. Too many communities, churches, American employers,” he tells TIME. “Of course, primarily, it’s these children who are American in every sense of the word except that they don’t have legalization.”

Garza and a staff of more than 60 aides have worked to build credibility in local Hispanic communities by conducting workshops several times a week to help immigrants — here legally and those here not — to pass their drivers’ license tests. Other courses help immigrants earn their G.E.D., learn English or even citizenship because, as Garza tells it, “you can talk about economic freedom and building a free society but in the marketplace, but millions of Latinos in this case are shut out of the marketplace because they don’t have a drivers license, or speak the language or have a diploma.”

At the same time, because of backing from the Koch Brothers, Garza knows that he can get a hearing from Republicans on Capitol Hill.

Whether it translates to progress, however, is still unknown. To this point, hardliners in the House have managed to repel efforts at broad change on immigration. Prospects for big legislation — especially with an election looming in November — are dim, and unrelenting negative coverage of the nation’s flawed immigration systems have moved few votes at the Capitol. The President ended protections for so-called Dreamers, the immigrants who came to the United States illegally as young children, and Republicans have not stepped in to reverse his order.

“I’m glad LIBRE seems to be raising its voice in a more concerted way and objecting to the direction of the Republican Party. But this is Trump’s party, and they don’t want a deal, they want an issue,” said Frank Sharry, the founder and executive director of the immigration-focused America’s Voice. “The only thing that will give Dreamers a chance is if Congress flips to Democratic control.”

Even so, LIBRE officials were on Capitol Hill this week giving lawmakers warnings that they’re ready to make another push, especially with an eye toward coming high-profile court cases. Garza’s team of organizers and activists, active in 10 politically important states, is ready to start once again at turning goodwill in the Hispanic and Latino communities into action.

“It’s a top priority for our network. We’re putting our money and our resources and our team where our mouth is,” Garza said.

While critics often see the Koch network as loyal yes-men to Republican leaders, that’s not always the case. For instance, the pieces of the Koch grassroots army are adamantly opposed to the Trump Administration’s trade and tariffs gamble. Groups operating under the banner of the Kochs have run ads criticizing the most recent spending bill — against Republicans who voted for the Republican Congress’ work. Charles Koch has taken a keen interest in overhauling the criminal justice system and has partnered on projects with the liberal Center for American Progress.

So when the Koch-backed groups ring, it’s a good bet White House or congressional officials pick up the line because it’s often not the assumed position.

Which is why the question of immigration has proved so frustrating. LIBRE and other parts of the Koch machine — including the powerful grassroots-focused Americans for Prosperity — have made clear they want a path for immigrants in the country illegally to earn citizenship, for children brought to the country illegally to be protected, for families who are stopped at the border to stay together.

“I’m going to be frank you with: there’s been some resistance,” Garza said. “We are taking a principled stand on this. Without regard to party or personality, we’re going to drive this advocacy forward for immigration reform. We will partner with whoever we have to leverage their voices.”

For folks like Garza, who has strong personal backing from Charles Koch in these efforts, the end results matter more than the process, and he acknowledges the immigration goals he’s pursuing are more closely aligned with liberals than with conservatives. “Normally, we’d be in disagreement with them on everything else,” Garza said. “Where we do align, and there’s a common interest, it makes all the sense to work together.”

For instance, there have been tentative conversations with the group formerly known as the National Council of La Raza, a group often vilified in the conservative press, and LIBRE refused to back House Republicans’ compromise immigration legislation because it lowered all immigration.

“For us, that was unacceptable,” Garza said. “If you made these policy decisions that would restrict legal immigration, then you would hinder the ability to address market forces and the private sector to hire who they need to hire. It would induce more illegal immigration or illegal crossings because the demand is still there.”

To be clear, pieces of the Koch machine promote free markets as a bedrock principle. That’s, in part, why hundreds of deep-pocketed donors pony up tens of millions of dollars to the network of advocacy groups, nonprofit enterprises and political committees that coordinate their activities.

For Garza, though, the objective is more personal. Although he was born in California, he spent the first 19 years of his as a member of a family that earned a living as a seasonal worker, making his way from Mexico north to Nebraska with his parents. He sees common experiences with today’s immigrants being used as political pawns.

“They go to church with us. They are our schoolmates. They’re our colleagues at work. There’s so much at stake. We cannot give up,” Garza said, leaning on politics as a way forward, even in the face of consistent disappointments. “As frustrating as it is, this is our legislative process. The only ones who can bring a true, long-term solution to this is Congress. It’s their responsibility to do that.”

Disclosure: Time Inc., TIME’s parent company, was acquired by Meredith Corp. in a deal partially financed by Koch Equity Development, a subsidiary of Koch Industries Inc.

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Write to Philip Elliott at philip.elliott@time.com.