McCullum was reported to be the leading candidate after a round of interviews led by the England and Wales Cricket Board's new director of cricket Rob Key at the start of the week.
It's understood he's leapfrogged previous favourite Gary Kirsten, and the process is moving towards a swift conclusion.
Moves were already under way on Wednesday to have Key's preferred nominee ratified by the ECB board, whose approval is likely to be swift, leaving contractual details and any work permit arrangements to be settled.
If all goes smoothly an announcement could come as soon as Thursday, but more time could be required to iron out the logistics.
The 40-year-old's current role in charge of Indian Premier League franchise Kolkata Knight Riders was one potential discussion point, but further negotiations may not be necessary.
Key had previously indicated there could be an element of flexibility around IPL employment given his decision to split the red and white-ball positions.
But the Indian Express newspaper reported that McCullum has already told KKR he will be leaving his post to take up the reins with England.
McCullum has never coached a first-class side before, let alone a Test nation, but boasts an unimpeachable reputation in the game as an astute thinker and inspirational skipper.
The former Brisbane Heat batter in the Big Bash, he made 101 Test appearances during a 14-year international career with the Black Caps, as well as 331 in limited-overs cricket, and was an active player on the Twenty20 circuit as recently as 2019.
His progressive, attacking philosophy aligns with that of newly-installed Test captain Ben Stokes.
Both Morgan and Stokes have been canvassed for their opinions on the candidates and both are likely to have given enthusiastic support to McCullum.
14°C