Pompey push for Powell
Powell is available on a free transfer after being released by Derby County earlier in the summer.
The tough-tackling midfielder has been training with Aston Villa and has attracted the interest of a host of clubs.
Pompey boss has held talks with Powell and he is hopeful of agreeing a deal to lure him back to the South Coast.
"I like him and I think he'd do well here. We need to strengthen in midfield," said Redknapp.
"But it all depends what he's looking for wages-wise. Darryl isn't with a club at the moment and has got to get fixed up."
Powell is considering all his options and he admitted he is attracted by a return to his old club.
"Harry Redknapp would like me to play for Portsmouth, so we will see where we go from here," said Powell.
"If things can be sorted out properly for me then there's a good chance I'll be coming.
"But before I come, I want to know that the club is going to be progressive. I've heard there might be one or two signings.
"Portsmouth is a club I have a lot of affection for. It is a club that could take off - but there are a few clubs like that. The taking off is the hard part.
"There is interest from the Premiership and first division. Clubs say they'd like to do something, but it's the doing it that's the really hard part."
Should Redknapp miss out on Powell he may switch his attentions to French midfielder Frederic Brando after he impressed on trial.
The 28-year-old is available on a free transfer after being released by Sedan and Redknapp is considering offering him a permanent deal.
"I thought Marlon (Frederic) Brando played well in midfield," said Redknapp. "He's on a Bosman and could be a contender, but my problem is I need to move on other players first."
One player who will not be joining Pompey is Dele Adebola after a short trial at Fratton Park.
Adebola is looking for a new club after being freed by Birmingham, but Redknapp had decided not to pursue his interest in the player.
"I wanted him to carry on training with us, but he's got other offers so it would be unfair to keep him here," said Redknapp.
