Conservative industrialist Charles Koch declined to back Donald Trump in last year's election. (Patrick T. Fallon for The Washington Post)

INDIAN WELLS, Calif. — Leaders of the influential Koch network on Sunday expressed opposition to President Trump's ban on refugees and immigrants from Muslim-majority countries, saying the executive order is not in keeping with their aims to build a free and open society.

“We believe it is possible to keep Americans safe without excluding people who wish to come here to contribute and pursue a better life for their families,” said Brian Hooks, the president of the Charles Koch Foundation, who is co-chairing a weekend conference of donors who help finance the Koch operation.

“The travel ban is the wrong approach and will likely be counterproductive,” he added. “Our country has benefited tremendously from a history of welcoming people from all cultures and backgrounds. This is a hallmark of free and open societies.”

The statement represents the network's first public critique of Trump since his election victory.

President Trump signed an executive order to halt U.S. entry for refugees, migrants and foreign nationals for 120 days starting Jan. 27. Fiery protests and lawsuits made for a tumultuous weekend. Here's what you need to know. (Dalton Bennett,Erin Patrick O'Connor,Katherine Shaver,Monica Akhtar,McKenna Ewen/The Washington Post)

Last year, Charles Koch, the conservative industrialist who leads the network, was sharply critical of Trump's proposal to ban Muslim immigrants from the United States, calling the idea “antithetical to our approach.” He called the suggestion that Trump might require Muslims to register “reminiscent of Nazi Germany.”

Koch did not weigh in on the ban Saturday night as he greeted 550 wealthy donors gathered in a courtyard under stately palm trees at a desert resort here. The 81-year-old billionaire, who pointedly declined to endorse Trump in last year's presidential election, praised the network's work in helping Republicans maintain their majority in the Senate and their support for state officials around the country.

He expressed optimism about what the group will be able to accomplish in the coming year, saying, “We may not have an opportunity again like we have today.”

In the 2018 cycle, the network aims to spend $300 million to $400 million on policy and political campaigns — up from $250 million during the 2016 elections. The money will be spread across a constellation of groups, including Americans for Prosperity (AFP), the Freedom Partners Action Fund, Concerned Veterans for America, the Libre Initiative and Generation Opportunity, which operate under the AFP banner.

This weekend's gathering is the largest since Koch began holding twice-a-year seminars with like-minded donors in 2003. Since then, he and his allies have built a political and policy operation with reach into 36 states.

No one from the Trump administration attended this weekend's conclave. However, five Republican senators made appearances: Patrick J. Toomey (Pa.), David Perdue (Ga.), Ben Sasse (Neb.), Mike Lee (Utah) and James Lankford (Okla.). So are two House members, Jason Chaffetz (Utah) and Marsha Blackburn (Tenn.). And three governors flew in: Wisconsin’s Scott Walker, Arizona’s Doug Ducey and Illinois’s Bruce Rauner.

Asked by reporters Sunday whether he wanted to weigh in on Trump's refugee ban, Chaffetz quipped: “Not really, but if you want me to, I will.”

The chairman of the House Oversight and Government Reform Committee expressed concerns about the specifics but said the move is generally on the right track.

“If we’re targeting based on religion, I think that’s wrong,” said Chaffetz. “I understand the need and support the idea that vetting from certain countries is needed. … A legal permanent resident I think is a different category. I don’t understand what they’re trying to do on those categories. People that have a green card supposedly have been vetted. So there needs to be some further clarification.”

The congressman withdrew his support for Trump in October after the revelation of a 2005 “Access Hollywood” video in which Trump talked about women in lewd terms.

But on Sunday, Chaffetz praised Trump for governing as he campaigned. “I support generally what he’s doing, and he’s off to a roaring start,” said Chaffetz, who might try to run for Senate in 2018. “I think he’s surprising a lot of people that he’s doing what he said he’s going to do. But there are those of us that actually support that.”

For his part, Lee ducked when asked by reporters about the executive order, saying he only wanted to talk about criminal justice reform, the subject of a panel Sunday morning

“We’re here to discuss a different issue and I’ve got to leave right now to go catch a flight,” he said.

Pressed by a group of reporters at the meeting, he added: “I wasn’t aware that I’d lose my First Amendment rights after walking out this door.”

Then Lee, a member of the Senate Judiciary Committee, walked out the door.