Renua leader Lucinda Creighton says a complaint to the Standards in Public Office Commission (SIPO) is part of a "dirty tricks campaign" against her.
She is claiming someone is trying to use SIPO "for political ends", adding that any such attempt is 'morally bankrupt'.
A similar complaint relating to alleged failure to declare 'benefit-in-kind' while she was a minister has already been dismissed by the commission.
Ms Creighton described the anonymous complaint as "cowardly politics", and called on the person who lodged it to come forward.
"It is critical we protect institutions of the state that have been set up to protect our citizens and uphold the law of the land," Deputy Creighton said in a statement.
"Those who would misuse such institutions obviously hold the democratic process in contempt. Their cowardly politics of the anonymous letter and the poisoned pen will not prevail," she added.
She says she believes this complaint was resubmitted in an attempt to taint her and her party's reputation ahead of polling day:
Renua is this afternoon launching a new policy on crime as part of its General Election campaign.
