Robson fears Dundee Utd losing Levein
He said: "It's going to be difficult to keep him at Tannadice because I wouldn't be surprised if a bigger club tried to take him away.
"Hopefully that won't happen because we love working with him but the fact he has done so well won't be going unnoticed.
"He was linked with the Scotland job and that wasn't a surprise because of how good he is.
"We want to hang onto him but it wouldn't be a shock if someone big came calling."