President Donald Trump ordered the firing of Robert Mueller, the special counsel overseeing the Russia investigation in June, according to four people on the inside, but backed down when White House counsel Donald McGahn II threatened to resign rather than carry out the firing of Mueller.

Trump denied the story Friday morning, dismissing it as “fake news.”

The development adds a new twist to the investigation of Russian involvement in the 2016 election and possible collusion with the Trump campaign. McGahn saw the firing of Mueller as disastrous for the Trump presidency, fueling suspicions of a cover-up, much as Trump’s firing of FBI director James Comey did months ago.

Mueller’s investigation into Trump and his allies as special counsel appointed to look into Russian interference has already led to the indictment of Paul Manafort, campaign manager of Trump’s 2016 election campaign at one time, and the indictment of Michael Flynn, as well as a guilty plea from campaign staffer George Papadapoulos. Manafort and Flynn, however, were indicted for crimes committed that were not particularly relevant to the election, prompting Manafort to sue Mueller for straying outside the mandate he was given as special counsel. Papadapoulos pled guilty to lying about his contacts with Russia to the FBI, and the New York Times reported that he told an Australian diplomat that Moscow had compromising information that would damage their 2016 election opponent, Hillary Clinton.