Marshall, 28, was left on the bench as the Lions beat Burnley at the weekend to set up an FA Cup quarter-final clash with Tranmere and after keeping two clean sheets, Wise is set to keep Willy Gueret between the sticks for Saturday's clash against Preston North End.
Marshall feels the move has turned sour, forcing him to admit "I might as well not be here"
"The place is buzzing, as you would expect, but I feel on the outside. I came here to play football and I can't really see the point if I'm not. I'm no better off than I was at Ipswich."
He added: "I played in two league games and did well in them both, but I wasn't able to play in the FA Cup fourth-round tie at Telford because I hadn't been registered in time.
"Dennis decided to stay with the same team for the Burnley game and it looks as if he will stick with it again this weekend
"To be honest, I can't see the point in me being here. I need games and I need people to see me playing, so this situation is not doing me any good."
Marshall has been offered a free transfer by Ipswich Town boss Joe Royle and had high hopes of moving to Millwall on a permanent basis as a replacement for Tony Warner, who is thought be leaving the club in the summer.