President-elect Donald Trump is expected to hold a news conference on Jan. 11 to address conflicts of interest, though an adviser said the date might shift. Evan Vucci

Some prominent conservatives have signed on to a letter warning President-elect Donald Trump that he needs to sell off his businesses to address his many conflicts of interest.

"Respectfully, you cannot serve the country as president and also own a world-wide business enterprise, without seriously damaging the presidency," says a letter sent Monday by a bipartisan group of politicians, ethics advocates and academics.

The letter was signed by several moderate Republicans, including former New Jersey Gov. Christine Todd Whitman, former Minnesota Gov. Arne Carlson and former Rep. Mickey Edwards of Oklahoma, who was chairman of the House Republican Policy Committee.

But the signers also include some further-right conservatives, including Peter Schweizer, president of the Government Accountability Institute, and political consultant John Pudner of Take Back Our Republic, which seeks to build GOP support for campaign finance reform.

Pudner was instrumental in the successful Tea Party-backed effort to unseat then-House Majority Leader Eric Cantor, a Virginia Republican. He also is a contributor to Breitbart News, which has been managed in recent years by Trump's senior counselor, Stephen Bannon.

A Trump supporter, Pudner said that cleaning up Washington had been a central part of the president-elect's campaign and that now he needs to follow through.

"He made such a theme of things like the revolving door and the ways in which decisions can be influenced, not for the public good," Pudner said. "If you have the presidency and people are going to question every week, 'Why is he making this decision? Is there some business angle on it?' I just think it undercuts so much of the reason that people did support him."

Other signatories included several good-government groups, such as People for the American Way, Public Citizen, Common Cause and the Revolving Door Project, as well as liberal Democrats such as Zephyr Teachout of Fordham University School of Law and Harvard Law School's Laurence H. Tribe.

Trump senior adviser Kellyanne Conway told CNN on Monday that a news conference is planned for Jan. 11 to address conflicts of interest. But she added that the date might shift, depending upon the advice of Trump's lawyers.

In the past, Trump has said he will turn over his companies to his grown children to operate.

The letter notes that the president-elect has begun to address some of the conflicts he faces, terminating real estate deals in Brazil, Azerbaijan and Argentina and announcing plans to close his charitable foundation.

"That is a good start, but we wish to be clear that the only way to solve the problems you face remains divesting your business enterprises into a blind trust managed by an independent trustee or the equivalent," the letter stated.

You can read the letter in its entirety here: Copyright 2019 NPR. To see more, visit https://www.npr.org.

Correction (2017-01-03 05:00:00 UTC):

A previous version of this story incorrectly said Zephyr Teachout is with Columbia Law School. She is with Fordham University School of Law.