Sunderland reportedly want to sign Sakho, as they look to bolster their forward options for next campaign.
However, Sam Allardyce is unwilling to part with the money that West Ham are demanding for the Frenchman.
The Hammers are willing to sell Sakho, as Slaven Bilic has plans to bring in a new big-money striker during the summer transfer window, but they will not sell cheap.
West Ham realise that Sakho would offer them good cover, and Sunderland are reportedly struggling to negotiate a deal.
Allardyce has already stated that he does not want to overspend in the upcoming transfer window, and he currently feels that a deal for Sakho does not represent value for money.
Sunderland are still apparently working on a deal, but if they are unable to get the transfer over the line they could turn their attentions elsewhere.
Sunderland also rate Swansea City striker Bafetimbi Gomis, and they could make a move for him instead, if they are unable to come to an agreement over Sakho.