It was originally thought that Blackwell would be confirmed in the Leeds hotseat sometime today.
The paperwork was expected to have been rubber-stamped with a two-year contract duly signed, but following a brief meeting with director Simon Morris, the situation now looks different.
"We are getting there," said Football Director Peter Lorimer, who had also been led to believe both he and Blackwell would be available for interview this afternoon following the confirmation of the appointment.
"We have always said it is the most vital decision this club has had to deal with for a long, long time. Whatever happens and whoever gets put in charge has a mega job on their hands and we want to make sure every angle is covered.
"We are doing that now, but it is not quite sorted out yet. Until it is, it's ongoing. All I can say is we are not quite ready. We have to look at other options should the one everybody thought it was going to be not turn out to be the right one."
There still remains the prospect that, should Steve Parkin conclude a deal, he will want his own man in place, leaving chairman Gerald Krasner and his directors looking rather silly for opting to undertake interviews and then unofficially handing the role to Blackwell.