The spokesperson for Bevan Chuang says she was pressured by members of the Palino campaign to reveal her affair with Auckland mayor Len Brown.
Mr Brown has admitted the two-year extra-marital affair, and an inquiry into mayoral office spending is under way.
Mayoral candidate John Palino lost to Len Brown in this month's local election by about 50,000 votes.
On Saturday, Mr Palino issued a statement denying any involvement in a campaign to unseat Mr Brown saying suggestions he orchestrated a conspiracy are absurd.
He has denied putting pressure on Ms Chuang but admitted to meeting her in an Auckland carpark on 13 October, the day after Mr Brown was re-elected.
Ms Chuang's spokesperson Hamish Price says she felt pressured to go public with the affair and that pressure came from the Palino campaign, including John Palino himself.
Mr Price told Radio New Zealand's Morning Report programme that Ms Chuang attests the meeting on 13 October was to discuss the role that she would play in embarrassing Len Brown into resigning.
"She's very open about the amount of pressure that was brought on her by various people within the Palino campaign, including John Palino, to take part in what was clearly an attempt to place so much pressure on Len Brown, embarrass him effectively into stepping down from the mayoralty."
Mr Palino said on Monday that he would not respond to what he called defamatory statements or lies.
In an earlier statement, he said he had met with Bevan Chuang after the election only to discuss threatening text messages they had both received from the same number.