Chelsea want around £60m (€69m) for the Senegal international, a figure that has so far discouraged serious offers from any of his suitors.
Aston Villa initially explored the possibility of a loan rather than a permanent deal, reflecting the financial caution around a player who spent last season on loan at Bayern Munich, where he scored 11 goals and added four assists in 34 appearances despite starting only 15 of them.
Chelsea's own thinking has shifted increasingly toward a sale. The club has strengthened its attacking options with the free transfer arrival of Danny Welbeck from Brighton, while João Pedro remains a central figure in head coach Xabi Alonso's plans up front.
With the squad still needing to be trimmed after a heavy summer of incoming transfers, moving Jackson on would ease the numbers game while recouping a significant fee.
Aston Villa and Tottenham remain the most concrete Premier League interest, while Atlético Madrid are also credited with monitoring Jackson's situation, though the Spanish club would likely need to resolve their own Julián Álvarez saga first, potentially pushing any move toward the very end of the window.
For all parties, the fundamental issue remains the same: until Chelsea's valuation shifts from its current £60m base, meaningful negotiations are unlikely to accelerate before the transfer deadline.
Jackson, who joined Chelsea from Villarreal in 2023 and is under contract until 2033, has previously worked under Unai Emery at Villarreal, a relationship that could work in Aston Villa's favour should their financial position allow them to meet Chelsea's demands. His combination of pace, pressing and off-the-ball movement continues to attract admirers despite occasional criticism of his finishing, and whichever club eventually signs him would be taking on a player who has already shown he can perform at Premier League and Bundesliga level.