The 26-year old winger joined the 'Well from English League One club Rotherham United on an initial four-month loan at the end of August and has scored four goals in his past four outings for a total of five in 12 in Scotland.
After Ainsworth netted in the 4-0 New Year's Day win over St Johnstone, McCall admitted he was hoping to tie him up for the remainder of the Scottish Premier League season.
"I think we are going to have to pay him a little bit more than we were paying which is unfortunate and we probably haven't got it, but he has scored four in four so the money keeps going up," said McCall.
"But we are hopeful. There was dialogue on Tuesday and hopefully it will be sorted in the next couple of days."
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