Sources familiar with the situation, who did not want to be named, told RNZ in December that Simpson was no longer a member of C&R.
When asked earlier this year, C&R president David Hay would not confirm Simpson had left.
But Hay has now told RNZ that Simpson resigned 18 months ago, but the group had not updated its website until recently.
He said C&R has been accepting candidate nominations for an Ōrākei ward councillor, a position currently held by Simpson, and for an Albert-Eden-Puketāpapa councillor ahead of the local body elections later this year.
The Albert-Eden-Puketāpapa ward has two councillors. C&R’s Christine Fletcher and City Vision’s Julie Fairey were elected to the roles in 2019.
Hay said C&R would announce their candidate selections soon.
Since news that Simpson was considering running for mayor of Auckland broke in January, she has not confirmed whether she would challenge Wayne Brown for the job.
She earlier told RNZ she would advise the public of her decision by the end of May at the latest.
Simpson has been approached for comment.
-RNZ