Special counsel Robert S. Mueller, is in talks with the West Wing about interviewing current and former senior administration officials, including recently ousted White House chief of staff, Reince Priebus. Mueller has asked the White House about specific meetings, who attended them and whether there are any notes, transcripts or documents about them. Among the matters Mueller wants to ask the officials about is President Trump’s decision in May to fire the F.B.I. director, James B. Comey. That line of questioning will be important as Mueller continues to investigate whether Trump obstructed justice in the dismissal of Comey.