“Magnier and McManus’ stake was going to be the key and we knew if that went to Glazer, then the club was at risk.”
Oliver Houston, of Shareholders United, told the ITV News Channel: "This is by no means over.
"Our message to Malcolm Glazer and to people daft enough to lend him all this money is that not only will you not be able to increase your profits but you are going to see a very sharp fall in profits.
"Manchester United is going to become an extremely tainted brand. People will feel that this is no longer their club."
Mark Longden, of the Independent Manchester United Supporters Association, said he was amazed by the decision of the Irish to sell their stakes.
He said: "They have sold the Manchester United heritage. They have proved that they were never ever interested in Manchester United, or football."
"If he does take over there will be no customers in the ground," he said.
Jules Spencer, chairman of the Independent Manchester United Supporters Association, said: “If this is to be the end then we will go down kicking and screaming.
“And if he (Glazer) does get control then we will do what we said, which is up sticks and form a new club which will continue the traditions and heritage and the legacy of 125 years of Manchester United.
“We don’t want Malcolm Glazer, we want a club run for the fans - and that is what we will do.”
Johnny Flacks, a season ticket holder since 1966 and former fans group spokesman, said: "This takeover would appear inevitable.
"It is disappointing in the sense that from what we have been told he does not appear to have the funds to back it up and the club is going to be saddled with an awful lot of debt.
"Glazer is no (Chelsea owner Roman) Abramovich.
"However I think the time is right for a change because complacency has set in at the club in the last three years, hence the results on the pitch.
"The board have told us we have got no money to buy players in the summer.
"I think a majority of fans will be against the bid and there will probably be a protest at the match on Saturday, but it is an away match so you are only talking about a few fans.
"The cup final could be more eventful."