Manager lines up replacement
Latics' manager said: "I offered Lee a new contract and gave him a deadline which has now passed.
"As he has not replied, I expect him to sign for someone else and wish him all the best."
Johnson added on a positive note that there are a lot of right sided midfield players on the market.
"I am hopeful of bringing in somebody of the same quality or even better," he said.
Croft was signed from Derby County on a season-long loan, but that became a permanent transfer in January when he had his contract with the Rams terminated.