Halford impressed during a loan spell at Pompey last season and has previously expressed a wish to be given an opportunity at Wolves next term.
However, Pompey have been keen to secure a permanent deal for Halford, who established himself at centre-half during his loan stint with the Championship club.
Though Cotterill brought in Jason Pearce from Bournemouth last week, he says he is still eager to add Halford to his plans for next season.
"We are still interested in Greg," Cotterill told The News. "We are interested in lots.
"There are quite a few targets we are still after and if they come across the line then great.
"What we are trying to build here is a squad. Sometimes you can't pick and choose how they come in and when they come in.
"You can have a strategy and you can write it down and contact the clubs of players you are interested in and do all of that. But sometimes they don't always drop in the order you want them to drop in.
"When they do drop you have to make sure you get them across the line very quickly."
Source: Team Talk
Source: Team Talk