Labour leader Phil Goff says he does not know whether MP Chris Carter believed his written apology about his ministerial expenses.
Mr Carter is on forced leave from Parliament, because of his handling of the row over ministerial credit card spending.
He has been told to spend the week working in his electorate.
Mr Goff says that, while he took the Te Atatu MP's apology last week to be genuine, he does not know if Mr Carter believed it.
"I'm not sure yet that he understands why a genuine apology is needed, and that taxpayers in New Zealand have the right to expect their money to be spent frugally and with reserve."
Mr Goff says he will talk with Mr Carter later in the week before making any announcement on his future position in the Labour caucus.
Mr Carter is declining interviews but told Radio New Zealand he is getting feedback from his local electorate and will return to Parliament refreshed and ready to work.