Pompey chief Mark Catlin is adamant Michael Eisner has been the only credible emergence as a potential owner.
Since coming under community ownership in April 2013, the Blues have received numerous takeover enquiries.
Yet none have progressed to the present stage involving Eisner and his Tornante investment group.
Trevor Birch, former joint-administrator when the Blues were last up for sale, is heading negotiations with the American billionaire.
The process is approaching a week into the 70-day due diligence process after exclusivity was granted.
Talks have this week continued between Pompey’s representatives and Eisner in America.
And Catlin believes the former CEO has towered above those to have indicated interest in the Blues.
He said: ‘There has been interest before, but none that has progressed to this stage, otherwise fans would have been told.
‘A lot of the others were speculative and wanted us to put a price on the club rather than come to us and say what they wanted to do with the club.
‘It was plain and simply all about money, there was no identifiable individual we received an offer from, so there has been no-one really credible.
‘However, if the right person came along with the right amount of resources it is something the board would look at in the first instance and then progress to the fans in the second.
‘The interest is flattering, it says what a great job we have done as a football club to get to this point, but ultimately the process now has to take its course and we have to let the fans have the final say on what direction it goes.’
During the ongoing process, Catlin insists there cannot be constant updates regarding progress of takeover talks.
He added: ‘There is a backstop of 70 days and I think it is unfair to put pressure on anyone at this point, specifically Trevor or Michael in regards of their negotiating process.
‘Trevor is negotiating and myself and a number of others at the club are compiling all the details as required by Michael Eisner’s team as part of the due diligence process.
‘Contractually we have to keep a tight lip on what is going on and that is correct and proper.
‘As I have said from the start of the process, we have to let the professionals do their job and get on with it.’