Oldham's interest in Evans, who was released from prison in October after serving half of a five-year sentence, has prompted widespread condemnation, with over 65,000 people having signed a petition urging them to reconsider.
Sponsors have also terminated deals with the League One club in response to the planned signing, but Corney expects a deal to be announced in the coming days following a "unanimous" decision from Oldham's board.
In an interview with the Jewish Chronicle, Corney said: "We believe he has served his time. There is an 80 per cent chance of us signing him. It won't be done today [Wednesday]. It’s not straightforward and there are some legal issues.
"There might be a cost implication, but you have to stick to your principles. We weren't surprised by the backlash."
Corney - who claims to have received messages of support from three unnamed Premier League managers, according to the Jewish Chronicle - is aware Oldham will face criticism should the deal go through.
"I completely understand people's views and I respect them. I would never tell people they are wrong to have their own views. But we want people to keep them in check," he added.
"I hope people don't get too carried way and it doesn't get too hot."
Evans, who has vowed to clear his name, played for Sheffield United prior to his arrest and subsequent jailing in April 2012.
United are among the clubs to have since distanced themselves from a move for the striker, amid a storm of public disapproval.
Oldham signed striker Lee Hughes in 2007 after the forward had spent three years in prison for causing death by dangerous driving.
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