Boss Joe Royle says he is approaching what he describes as "top Premiership clubs" regarding the availability of some of their fringe players. Royle wants to sign two defenders ahead of the start of the new season.
Former loanee David Unsworth is at the head of Royle's list, however Portsmouth seem less than keen to settle the remaining year of the former England man's contract or pay part of his wages while he spends the season on loan with Town.
In addition, the full-back or centre-half is reported to be back in manager Alain Perrin's plans, while it is also understood there may be interest from other Premiership clubs in the ex-Everton player.
Royle says he is still not ruling out Unsworth returning to Portman Road, but he is also casting his eye elsewhere: "We are still looking to bring in at least one new defender before the start of the season.
"We are waiting to see if the situation regarding Unsy is going to change, but we are not oblivious to other players who could come into the reckoning.
"With this in mind we are in contact with top Premiership clubs about players who might not be expected to figure regularly in their first teams in the new season."
Last summer Town were close to signing young Arsenal defender Justin Hoyte on a year-long loan and it could be the Blues are after a player at a similar stage in his career this time around.
Hoyte eventually remained at Highbury after the Gunners failed to secure the signature of Ajax's Hatem Trabelsi, Arsene Wenger requiring the England U21 international as cover.