O’Brien, who joined Nottingham Forest from Huddersfield Town last summer, has so far featured in 17 games for Steve Cooper’s team, scoring a lone goal.
He has attracted big interest in the January transfer window and is now all set for a move away from the City Ground.
Forest have in fact cleared the player to head for a medical at Blackburn, with a deal now set to be completed before the deadline.
Jon Dahl Tomasson’s side, who are placed fifth in the Championship table, will sign the player on loan with the guarantee of a possible £10m deal for O’Brien if they eventually secure promotion.
Other suitors West Brom and Sheffield United have not been able to match the offer put up by Blackburn.
The Riversiders are also actively looking for a defender and have yet another Nottingham Forst player, Steve Cook, on their radar.
However, it has been suggested that Cook will now remain at the City Ground beyond the closure of the window.
