The Hammers have enjoyed a mixed 2014/15 season, with their early form having tailed off, killing initial hopes of a challenge for Champions League qualification.
Song was a major force in their fine performances, but his own displays have slipped, and it looks unlikely that he’ll be kept on after his loan spell from Barcelona due to this and the fees needed for his services.
West Ham are already looking at building beyond the Cameroonian’s stay, and have targeted Obiang.
A bid of around £4.5m is believed to have gone in, but even with the add-ons in place, it falls some way short of the £7m the Italian side wants.
However, reports suggest that the Londoners are confident of doing a deal eventually.
The Spaniard, 23, has netted three goals in 27 Serie A matches and has been capped by La Roja’s U-21 side.