Washington: William Barr has been Attorney-General for just one week but is on the cusp of staring down what will almost certainly be the most consequential decision of his long career: how much of the special counsel's findings to make public.

The position catapults him from Justice Department outsider free to theorise and speculate on special counsel Robert Mueller's investigation to the man at the centre of the legal and political firestorm that will accompany its looming conclusion.

In the hot seat: US Attorney-General William Barr. Credit:AP

With Deputy Attorney-General Rod Rosenstein preparing to exit after supervising the day-to-day investigation for nearly two years, and with Trump loyalist Matthew Whitaker now replaced in the top job, Barr is in the hot seat: He is responsible for navigating the department through congressional and public demands for details of Mueller's findings while dealing with a White House that may challenge – or even stifle – the conclusions.

Friends say Barr is accustomed to pressure-cooker situations by virtue of his experience as attorney-general from 1991 to 1993 under President George H.W. Bush, and other senior Justice Department jobs. He oversaw the department's response when Los Angeles erupted in riots after the Rodney King verdict and when Cuban inmates took hostages at a federal prison in Alabama. He blessed Bush administration pardons in the Iran-Contra scandal and offered legal advice on the White House's ability to invade Panama.