From The New York Times:

“The special counsel, Robert S. Mueller III, has obtained a letter that President Trump and a top political aide drafted in the days before Mr. Trump fired the F.B.I. director, James B. Comey, which explains the president’s rationale for why he planned to dismiss the director.

“The May letter had been met with opposition from Donald F. McGahn II, the White House counsel, who believed that some of its contents were problematic, according to interviews with a dozen administration officials and others briefed on the matter.”

For the full article: https://www.nytimes.com/2017/09/01/us/politics/trump-comey-firing-letter.html