Paul Manafort, the former chairman of Donald Trump's presidential campaign, has been told by federal prosecutors that they plan to indict him, The New York Times reported Tuesday.

The warning came after the FBI raided his home in July, even picking the lock, although he was at home asleep, the Times reported, citing two sources close to the investigation. Agents sought proof he had set up offshore bank accounts, and, the Times says, they took photos of the expensive suits in Manafort's closet.

As a result of Tuesday's report on the indictment threat, Senate Judiciary Chairman Charles Grassley, R-Iowa, seems resigned to the idea that Manafort will not be testifying before his committee, CBS News' Alan He reports. And even if he did appear, the committee wouldn't get any information from him, Grassley told reporters Tuesday, outside the committee room. He added that he would look into what the committee practices are on congressional testimony when the a witness is under indictment.

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The chairman mentioned one ongoing irritant where Manafort is concerned, though. "We have tried to make for weeks trying to get our phone calls returned from his lawyers and they haven't returned the phone calls," Grassley said.

On Monday, CBS News confirmed Manafort had been wiretapped under a foreign intelligence warrant in connection with U.S. concerns that he was communicating with Russian operatives who wanted to influence the American election. The warrants were issued before Robert Mueller was appointed as special counsel to take over the investigation from the FBI.

The U.S. government listened in on Manafort's conversations during the presidential campaign and through the election -- though not constantly -- and its surveillance includes the period when Manafort was Mr. Trump's campaign chairman.

CBS News' Andres Triay and Alan He contributed to this report.