CSX on Friday said it would extend the deadline for nominations to its board of directors.
The deadline for board nominees had been Feb. 10 but has been extended to Feb. 24.
Harrison retired early from Canadian Pacific last month and has teamed up with Paul Hilal of Mantle Ridge to seek a management change at CSX.
News reports have said CSX and Harrison have had discussions about that prospect, but the number of seats on the board supported by Mantle Ridge has been a sticking point.
In retiring early from CP, Harrison gave up tens of millions in compensation in exchange for CP giving him a limited waiver of a non-compete clause.
If Harrison is successful in becoming the CEO of CSX, he would replace Michael Ward, who has said he plans to retire by 2019.