The 22-year-old former Whites man rejoined the Elland Road club in January on an initial one-month loan.
Delph's loan is due to expire in two weeks' time and Leeds are hoping to retain the talent for as long as possible.
McLeish insists no decision has been taken over his immediate future and they will review Delph's position at the end of February.
"We haven't made any plans to extend anything at the moment," he is quoted in the Yorkshire Evening Post.
"We'll take stock when the month is up and have a look at things again."
Delph has made three Championship starts for Leeds and McLeish believes current form will dictate whether he returns to Villa's line-up.
Asked if Delph had indicated a desire to remain at Elland Road, McLeish said: "Not as such. I heard that he said that in the first few days, but I haven't spoken to Fabian.
"If he's playing well he might see there's an opportunity for him here. We hope he'll come back at a level where he says to us 'there's no way you can leave me out now'."