Stewart told BBC Radio Humberside: "At the moment I don't know whether I'll get a new contact at Manchester United or not.
"At the moment my main focus is to be playing well for Hull and try and extend my loan."
Stewart spent a spell at Yeovil on loan earlier in the season, but since moving to Hull has found the sort of form that Tigers' manager Nigel Pearson was hoping he would.
Stewart added: "At the moment I've not spoken to anyone at United about contracts so I'm not sure really. Being in the first team here (Hull City) is a lot better for me because everyone can see what I'm doing."
Source: BBC Sport
Source: BBC Sport