O’Brien was wanted by the Whites last summer, but the move failed to materialise back then and he continued with the Terriers, amid Leeds being unwilling to meet his asking price.
After staying on at the Terriers, O’Brien impressed for them in the Championship and has been an integral part of their push for promotion.
The midfielder took the pitch 43 times for Huddersfield in the Championship in the regular season and even registered three goals and three assists.
Huddersfield take on Nottingham Forest later today in the Championship playoff final and the result of that one game may determine if Leeds can secure the signing of O’Brien.
The Whites risk losing out on the midfielder if the Terriers secure Premier League football for next season.
Huddersfield are planning to offer a new contract to the midfielder should they go up and they also plan to increase his release clause.
The Whites are expected to be ready to meet his £10m fee but the Terriers themselves may stand in the way if they are promoted.
