McDonald, 23 joined the Blades last summer, signing a one year deal after being released by Burnley and immediately helped guide United to the play-off final - though he missed the final at Wembley due to injury as the Blades lost on penalties to Huddersfield Town.
He told BBC Radio Sheffield: "I'd like to say I'm fully confident of being back next season but I'm not in a position to do so at present. I want to get it sorted out soon and if they offer me the right deal I'd be delighted to sign." He added: "My agent has been speaking to the club a couple of times a week and we're waiting to hear back from them. No one else has made me an offer."