The special counsel, Robert S. Mueller III, needs to prove before Mr. Trump would agree to an interview that he has evidence that Mr. Trump committed a crime and that his testimony is essential to completing the investigation, said Rudolph W. Giuliani, the president’s lead lawyer in the case…

Mr. Giuliani acknowledged that Mr. Mueller was unlikely to agree to the interview demands. Mr. Mueller could subpoena Mr. Trump to answer questions if he does not agree to voluntarily sit for an interview. Mr. Giuliani left open the possibility that the president, who has said in the past that he would be eager to sit down with the special counsel, would still agree to be interviewed.

Mr. Giuliani appeared to be in part trying to shift responsibility onto the special counsel for the lengthy negotiations over an interview — and was most likely prolonging them himself.