New York (CNN) Donald Trump's sons, Donald Jr. and Eric, are actively involved in his transition efforts, sources say -- raising questions about their dual role in his administration and businesses.

Donald Trump Jr. helped vet and interview candidates for the interior secretary position, a source familiar with the process confirmed, and Eric Trump was present for at least one meeting for secretary of state between his father and Mitt Romney.

CNN reported last week that Trump Jr. was heavily involved in the opening at Interior, in large part due to his hunting passion. He has played a heavy role in picking that nominee, which is Montana Rep. Ryan Zinke, transition sources confirm.

The pick was expected to be a western state politician given Trump Jr.'s background. He is part of a conservationist hunting club called the Boone and Crockett Club, based in Montana, which Zinke represents. Trump Jr. and the transition have also gotten input from Montana Republican Sen. Steve Daines, who has been hunting with Trump Jr. and his son. A transition source said the Trump children's natural inclination toward conservation was weighed heavily in the search, balanced against other traditional Republican priorities of small government and less federal control of public lands.

A source close to the process said the children's involvement is only natural given how much Trump trusts their opinion and how well they know their father. They've long been a key part of his executive team at his organization, and their involvement in building his administration is an extension of that.

But at the same time, that history with the organization is exactly the problem, critics say.

Trump has faced frequent questions about how he will manage his potential conflicts of interest between his business empire and his administration. He has said he would have his children manage the company, but experts say that only a blind trust would be enough to satisfy ethical concerns -- admitting that Trump's situation is complicated.

Trump postponed a previously teased press conference planned for this week, which he had repeatedly said and tweeted would be the forum to answer questions about untangling his administration from his business dealings. The press conference will now be in January, his team says.

The new plan will reportedly involve Eric and Donald Jr. managing the business with non-family help, presumably freeing Ivanka to have a formal role in her father's administration. She and her husband, Jared Kushner, have been house hunting in Washington, and Kushner is also expected to play at least a key informal role in the administration.

But Eric and Donald Jr.'s roles in the transition have given fodder to ethics experts who say that even without their formal involvement in the administration, their closeness to their father mean there would not be enough of a firewall between the business and the White House.

The transition did not respond to a request for comment about the potential conflicts.

The Democratic National Committee criticized the role of Trump's children in the transition.

"Donald Trump's adult children cannot run the business and simultaneously have a role in Donald Trump's transition without the appearance President-elect Trump's decisions are for the good of the Trump Organization instead of the country," said Eric Walker, DNC deputy communications director in a statement.

Ivanka, Donald Jr. and Eric were also all seen in a meeting Trump held with big Silicon Valley executives Wednesday at Trump Tower.

Sean Spicer, a spokesman for the Republican National Committee who has been working closely with the Trump team on the transition, told CNN's Kate Bolduan that only "sneaky" dealings are a problem.

"You tell everyone, here's what's going on, here's the process, here are the people that are playing a role, that's being transparent," Spicer said. "Conflicts of interest arise when you're not -- when you're sneaky about it, when you're shady about it, when you're not transparent about it."