The deal was first reported by The Wall Street Journal.
The New York real estate magnate is expected to announce an announcement next week, and he will make his endorsement public on Monday.
Trump has long backed the Blackstone acquisition, saying it is one of the best deals in real estate history.
“We’re going to be able to make a lot of money on that property,” Trump said in December.
“The Blackstone deal is going to give us tremendous leverage to buy some very valuable properties,” Trump told The Wall St. Journal in December, “because you’re going a lot lower.”
The real estate deal would be a significant coup for Blackstone, which is in the midst of a $1.2 billion acquisition of the struggling St. Regis Hotel in Washington, D.C. The St. Regulation Hotel, which opened in March, is not only a tenant at the new Trump International Hotel in D.D.C., but also has a restaurant and other properties in New York.
The deal would not be complete for two years, but Blackstone has been in talks with the Trump Organization about a possible sale.
Blackstone is owned by Jeff Bezos, who owns The Washington Post, Amazon, and other companies.