Labour says National's Mt Albert by-election candidate should have attended a meeting on super-city governance, instead of a community watchdog meeting in the electorate on Monday night.
Melissa Lee sent apologies to a meeting held by the Public Service Association, saying she had a long-standing engagement with the Avondale Neighbourhood Watch.
About 60 people attended the super-city meeting, with other candidates saying the public had a right to hear from the Government about its plans for Auckland governance.
Labour candidate David Shearer says Ms Lee's absence was a miscalculation by the National Party.
The Mt Albert by-election is to be held on Saturday. Labour has held the seat since it was established in 1946.