And the Blues’ chief executive admits talks remain ongoing with Marcus Harness’ representatives over the leading scorer’s Fratton Park future.
Pompey have 12 players out of contract at the season’s end, in addition to five loanees returning to parent clubs.
Among those whose deals are expiring are Sean Raggett, Michael Jacobs, Reeco Hackett, Louis Thompson, Shaun Williams and, of course, Harness.
In the cases of Harness, Hackett and Thompson, the Blues possess club options, enabling them to extend the player’s stay by another 12 months.
Although an alternative would be tabling a fresh contract to keep them at Fratton Park longer.
And with the transfer window now closed, Pompey have turned their attention towards retaining their best assets.
Cullen told The News: ‘I spoke to an agent last week, totally unrelated to Pompey, and he told me players were already calling him up on February 1 asking what was happening about their future!
‘As far as we are concerned, the contract situation will develop at an individual pace, player by player.
‘We will look at it on a case-by-case basis. Some will be very keen to get the future sorted, others may want to take a bit of a longer-term view and see what's out there at the end of the season.
‘They will go at different paces.
‘We speak to Marcus Harness’ agent regularly and there’s an option on him. There’s always discussions to be had with an agent because you look at each situation on its merits.
‘We are now structuring the squad for next year, so it’s really important to know what you’ve got in the building.
‘There are options you might want to exercise, players that haven’t got those options but you’d like to keep – then making the squad stronger with fresh blood coming in.’
Also out of contract this summer are Paul Downing, Callum Johnson, Jayden Reid, Jay Mingi, Ollie Webber and Aiden O’Brien.
Meanwhile, Gavin Bazunu, Mahlon Romeo, George Hirst, Hayden Carter and Tyler Walker will be returning to their parent clubs.
Although Downing, who is presently on loan at Rochdale, will be an obvious departure.
Cullen added: ‘It’s a two-way process with these contracts, making sure the fit is right, the marriage is right, for next season and beyond.
‘You have players who want to be here just as much as we want them to be a part of it, so it’s making sure that’s right and then having those discussions.’
A message from the Editor, Mark Waldron
You can support our local team of expert Pompey writers by subscribing here for all the latest news from Fratton Park for 9p a day, thanks to our 30%-off transfer window deal.