Some of President Donald Trump's Cabinet members are finding it difficult to rid themselves of $1 billion worth of assets they agreed to sell within a set time frame to avoid potential conflicts of interest, The Wall Street Journal reported.

The reason: A WSJ review found almost three-quarters of those assets are held in illiquid assets such as real estate, closely held companies, and stakes in private-equity funds.

Secretary of Education Betsy DeVos has pledged to sell assets worth at least $158 million, including investments in 102 companies that correlate in some way within the context of the work she will conduct for the government.

"With regard to each of these entities, I will not participate personally and substantially in any particular matter that to my knowledge has a direct and predictable effect on the financial interests of the entity until I have divested it," DeVos wrote to the U.S. Office of Government Ethics ahead of her confirmation hearing.

Some of her assets are in companies that provide "early childhood education, digital textbooks, and online tools for special education," according to the Journal.

Other Cabinet members having issues selling off assets are: Trump's deputy assistant to the president for international economic affairs Kenneth Juster, Energy Secretary Rick Perry, Treasury Secretary Steven Mnuchin and Secretary of State Rex Tillerson. 

• Relief Over Tillerson at State Department Replaced by Unease
• Tillerson: Travel Ban Vital for US National Security