Now some of the witnesses named in the report, who have departed the White House but rely on access to Mr. Trump for their livelihoods, fear his ire. Some have begun calling current and former administration officials and others in the president’s orbit to seek clues about Mr. Trump’s state of mind, according to four special counsel witnesses who spoke on the condition of anonymity.

One called friends and colleagues in the days before the report was released to see whether he could have the Justice Department redact his name from Mr. Mueller’s report, according to two people told of the matter. The idea went nowhere…

And even if the witnesses escape Mr. Trump’s wrath for now, they could find themselves in the cross hairs later if they are called to testify on Capitol Hill as Democrats scrutinize the president. The Mueller report provided a road map for congressional Democrats, whose leaders came under increased pressure on Friday to begin impeachment proceedings when Senator Elizabeth Warren of Massachusetts called for moving toward Mr. Trump’s ouster, the first major presidential candidate to do so.