Rangers are ready to try and tempt Madjid Bougherra north of the border, skysports.com understands.
Real Betis failed with a bid for the Algerian international last month as they came up short of Charlton's valuation.
Betis are understood to have bid £1.6million but it is believed The Addicks want at least £2.5million for the central defender.
The 25-year-old moved to the Valley just over 18 months ago and he has become a huge fans' favourite.
But his displays have attracted interest from elsewhere with Rangers now joining the hunt.
However, there is also Premier League interest in the African stopper.
Portsmouth, Middlesbrough, Newcastle and Wigan are all understood to be keeping close tabs on the situation and could be tempted to make a move.