The Trust said on Thursday that they have £1m banked, plus pledges from fans worth a further £2m. Four fans have pledged six-figure sums.
The Trust and Balram Chainrai, a former owner of the club, are the two candidates seeking to buy the club. Chainrai is currently owed £17.5m by the club.
Trevor Birch, the club's administrator, has said the club will be liquidated on August 10 if no deal is struck to pay off three players – Tal Ben Haim, David Kitson and Liam Lawrence – currently contracted to the club.
Nwanko Kanu, who has left the club, is also claiming £3m in unpaid wages.
Michael Appleton, the Pompey manager, has several trialists lined up to sign if the Fratton Park club can get over the financial hurdles.
"I think if the three remaining senior players left then I would be given the green light to move straight away and sign players," Appleton told BBC Radio Solent.
"But I'd like to think over the next few days I would be given the opportunity to speak to Portpin [Chainrai's company] and come up with a different solution.
"We've got a few players in on trial who are waiting for me to be given the green light so I can sign them. There are certain players in there I would sign very quickly.
"You've got to give them a little bit of credit for being so patient as they are desperate to get a contract. Next Friday is looming and we want to be in a position where we can get on with things."