Peter Dutton has warned Labor MP Susan Lamb's citizenship woes are not going away after she vowed to contest the next election without taking further steps to renounce her British ties.
The home affairs minister says despite Ms Lamb's "sad, sorry story" about family breakdown, she is clearly in breach of the law and is testing the patience of people in her Queensland seat of Longman.
"This story hasn't stopped, it's not going away, and I think you want to watch this space over the next few weeks," Mr Dutton told 2GB radio on Thursday.
Ms Lamb believes she is eligible to be a member of parliament because she took all reasonable steps to renounce her dual citizenship before nominating for the 2016 election.
The Queenslander tearfully revealed in parliament last week she could not prove her UK citizenship has been renounced because her mother walked out on her when she was six.
Ms Lamb told parliament she was unable to obtain a crucial copy of her parents' marriage certificate - which the UK Home Office requires to complete its paperwork - because of her estrangement from her mother.
However, her stepmother has told The Courier Mail Ms Lamb had a relationship with her biological mother into her adulthood.
The Turnbull government has repeatedly threatened to refer Ms Lamb to the High Court if Labor does not act first, characterising it as a test of Bill Shorten's leadership.
But their attacks have been blunted by Barnaby Joyce's extramarital affair and accusations the deputy prime minister breached ministerial standards.
Labor senator Katy Gallagher will face a High Court hearing next month to determine whether she took all reasonable steps to renounce her British roots.
"That will have a direct impact on some of these cases as well," Mr Dutton said.
Mr Shorten last week offered an olive branch to Prime Minister Malcolm Turnbull over Ms Lamb's citizenship issues, saying Labor would refer her to the High Court, but only if the government follows suit and refers its own MPs who are in similar circumstances.
Australian Associated Press