Mr. Manafort’s associates say he feels betrayed by the former business partners, to whom he collectively steered millions of dollars over the years for consulting, lobbying and legal work intended to bolster the reputation of Viktor F. Yanukovych, the former president of Ukraine. Mr. Manafort has told associates that he believes Mr. Mueller’s team is using the business partners to pressure him to flip on Mr. Trump in a manner similar to the one used to prosecute the energy giant Enron in the early 2000s by a Justice Department task force that included some lawyers now serving on Mr. Mueller’s team.

“Anybody who is a student of the Enron prosecution sees a very close parallel,” said Michael R. Caputo, a former Trump campaign operative, who has known Mr. Manafort for three decades and spoke with him on Wednesday. Another associate said Mr. Manafort and some of his close allies were reading a book by the conservative lawyer and commentator Sidney Powell that claims misconduct in the Enron prosecution. And Mr. Caputo, who was interviewed by Mr. Mueller’s team last month, said that “when Paul decided to fight, he knew the lay of the land.”