The 20-year-old spent the final three months of last season at United, and Blackwell is keen for the Wales international to return.
Blackwell told the club's official website: "Cotts wants to be here and we would love to have him.
"We're continuing negotiations with Wigan, although there are a couple of stumbling blocks at the moment.
"He made a great impression last season and his pace and trickery would be a real asset for us in the forthcoming campaign.
"I remain hopeful that we can make it happen on our terms, but in football you can never say it will definitely happen because things can change so quickly."