The former Cardiff City captain, 24, was often linked with a move to Anfield during Brendan Rodgers’ time in charge – with the former Liverpool manager having worked with the English defender during a loan spell at Swansea.
Reports earlier this month indicated that current boss Jurgen Klopp was keen to add an experienced defender to his ranks after the series of injuries to his centre-backs this month, with Borussia Dortmund’s Neven Subotic reportedly his first choice.
But Dortmund appear to have refused a move for Subotic and now Liverpool have turned to Caulker – who has had little playing time at Southampton this season and therefore Liverpool hope his temporary deal at the south coast club can be cut short in order to allow a move to Merseyside for the rest of the season.
Caulker joined Southampton on a season loan last summer following QPR’s relegation, but has started just one league game for Ronald Koeman’s side this season.
Mamadou Sakho and Kolo Toure should be back available for the home match against Arsenal on Wednesday, while Dejan Lovren could return for the FA Cup replay against Exeter next week. Martin Skrtel faces another few weeks out.
Liverpool would be his eighth club of his career so far.
UPDATE: Liverpool are attempting to push through the move today (Tuesday) so that Caulker can be registered in time to face Arsenal tomorrow night at Anfield. He could train with the Reds this afternoon.