It is understood Short has drawn up a shortlist of potential successors headed by a man he believes can reinvigorate the squad for a seven-game run-in which will determine where the Black Cats will play their football next season.
They are currently just a point above the Barclays Premier League relegation zone after a run of eight games without a win.
Former England boss Steven McClaren, whose second spell at Dutch club FC Twente came to an end last month, was swiftly installed at the top of the bookmakers' list of candidates, although sources close to the 51-year-old have since distanced him from the speculation.
It is understood there had been no contact with former QPR manager Mark Hughes, while the man who took the Champions League trophy to Chelsea, Roberto Di Matteo, is not thought to be interested.
Former Swindon boss Paolo Di Canio's odds shortened considerably overnight while Brighton's Gus Poyet was also receiving strong support, although Sunderland are keeping their own counsel over their main target.
What is clear, however, is that Short is determined to make an appointment sooner rather than later ahead of a difficult run of games which takes the Black Cats to Chelsea next weekend ahead of a derby trip to Newcastle and the visit of Everton, whose 2-0 FA Cup quarter-final replay victory on Wearside last season had such devastating consequences for O'Neill's reign, to the Stadium of Light.
The new man will be Sunderland's fifth manager in a little more than four years, and the first the Texan will have chosen since Niall Quinn's departure as chairman.
And Coppell feels that tendency to chop and change is indicative of the approach of overseas owners.
"You can only presume there was some dialogue after the game," he told BBC Radio Five Live.
"We are in the realms, I'm afraid, of spoilt-brat reactions because it is their toy.
"They don't understand the history and heritage of British football - there are so many foreign owners, I have nothing against that, but there is a way of doing things in English football that has now gone out of the window."
O'Neill did not appear to be expecting to pick up his cards as he conducted his post-match press conference yesterday afternoon.
Asked if a second-half fightback against United had given him hope for what lay ahead, he said: "Of course, very much so. There's still a strong determination in the dressing room."
Whoever does accept the job faces the task of galvanising a dispirited squad for a task in which they cannot afford to fail, with the financial implications of the new broadcasting deal meaning relegation is simply not an option.
Sunderland have, at times during a run which has seen them collect just three points from the last 24 on offer, been little short of abject and their lack of goals - they have scored just seven and conceded 12 in the process - has been brought into sharper focus by the loss of leading scoring Steven Fletcher through injury for the remainder of the campaign.
Skipper John O'Shea acknowledges that is a situation which cannot be allowed to continue if they are to escape the drop, and he insists January signing Danny Graham cannot bear that burden alone.
He said: "Look, it's so blatantly in front of us. Everyone just has to take responsibility, whether it's scoring from set-pieces, midfielders having shots, scoring goals.
"From last season, it's been a poor return from everyone in that sense, and that's something we will have to work on.
"You need that bit of quality to score goals and create chances, and that's something we are going to have to keep working on and keep believing that we can do it.
"It's going to have to happen at some point because obviously we are missing Fletch, who has been fantastic for us.
"It was hard for Danny in that lone role up top working his socks off. We need to get more support for him and better quality."