The influential defender is under contract until the summer of 2003 and the manager wants to avoid losing him on a Bosman free transfer.
"We've got to have an indication from Darren, because if he doesn't sign within the next 72 hours obviously we've got to take some action.
"However, I am optimistic, but I need an answer quickly.
"I can't allow the situation to fester and we've got to do something about it.
"I'm looking for a decision by Monday morning, because we've put a really good offer to him.
"If not we'll have to look for a replacement because I'm not going to let him walk away for free."
Only last week Bruce made Purse the new Blues team captain following the departure of Martin O'Connor to Walsall.