Current right back Stephen Wright was initially injured during the League Cup win against Aldershot and was thought to be ok, only to fail a late fitness test with an Achilies injury before the away game at Barnsley.
Aron Gunnarsson and Marcus Hall have been employed as caretaker right backs, but them playing out of position has left the team formation unbalanced.
"We're hoping to have something done by the end of the week in terms of bringing in a loan player at the right back position," said. Coleman to the club website.
"Wrighty's still injured so we'd like an extra option at that position at the moment so hopefully we can get something done in the next few days."
Meanwhile, Alexy Smertin who was released by Fulham yesterday is doing the rounds as a possible new boy. However, the Russian would need clearance by the Home Office first.
Another possible target Richard Duffy, played for Portsmouth Reserves in a 3-1 win at Fulham's Motspur Park last night.