The Cook Islands party is seeking legal advice on whether it can challenge the residency permit granted to Mark Lyon in court.
The secretary of the opposition party, Temu Okotai, says there are three areas they have concerns about.
These include money paid into a trust account and the prime minister, Dr Robert Woonton, who is also the immigration minister, over-riding the immigration service decision not to grant a permit.
Mr Okotai says they also have issues about the involvement of Mr Lyon's lawyer, MP Norman George.
"IN: Of concern to us is any legal implications to the conflict of interest for Norman George who is the chief adviser to the prime minister and minister of immigration as well as Mark Lyon's lawyer, because it is our belief that the permit was issued not at the recommendation of any government official or those involved with normal procedures - that it was an intervention of the prime minister."
Mr Okotai says given the widespread opposition to Mr Lyon being granted a permit, he can't understand why the prime minister and Mr George have taken the stance they have.