The midfielder only player a small role in Wigan's promotion and the former Crewe and Bradford man wants a move.
King said: "I am still looking to bring in two or three players to add to the squad.
"Whalley has been down today and we have agreed on something, but he is going back home to think about it over the weekend.
"He still has a place in Cardiff which may help us in terms of location, but his family are in Manchester and has a decision to make.
"He is a quality midfielder and has played in The Championship for the side who won that league last year so he has something about him.
"We have spoken and he is going to give me an answer after the weekend."
Meanwhile Swindon are also interested in ex-Gillingham skipper Paul Smith, the player walked out on the club this week.