Bu the president expressed little frustration or anger over the slur, and told a confidant that he did not believe Kelly would say something like that, The New York Times reported on Wednesday.
Trump called it “fake news,” and he repeated it in a pair of tweets.
Trump, however, believes that Kelly is concealing information from him, particularly about the pasts of White House staffers, who either opposed him during the 2016 presidential primaries or had connections to the Bush family, Presstv reported.
Trump has complained about Kelly to several friends and supporters, and has insisted to friends and political allies that he alone is responsible for his successes in office, such as the recent progress in relations with North Korea, the Times reported.
Meanwhile, Kelly has complained to some White House staff members that he doesn't "need this," after Trump gave him a lecture, and that he has given the impression that he does not think highly of the president, according to the Times.
There have been speculations for months that Trump's relationship with Kelley is deteriorating, and that the chief of staff is on his way out at the White House.
In March, Trump fired Secretary of State Rex Tillerson, who allegedly called him a “moron” after the president suggested a 10-fold increase in the US nuclear arsenal during a meeting at the Pentagon.
A few days after the report, Trump harshly criticized Tillerson in an interview with Forbes magazine, suggesting that he's smarter than the top US diplomat.
In March, Trump also fired National Security Adviser Lt. Gen. H.R. McMaster, whose relations with Trump had been strained over months.