Federal Labor insists it's only fair that if backbencher Susan Lamb is referred to the High Court over dual citizenship woes then government MPs are sent too.
The Turnbull government is seeking the resignation of Ms Lamb and has threatened to use its renewed majority in the lower house to refer her to the High Court.
Labor frontbencher Chris Bowen said the Queensland MP clearly took reasonable steps to renounce her UK citizenship.
"We are very very confident in Susan Lamb's case," he told Sky News on Monday.
The British Home Office did not accept Ms Lamb's application to renounce her citizenship and she failed to supply them with a copy of her parents' marriage certificate, The Australian reports.
Mr Bowen said Labor was happy to have Ms Lamb's case tested in the High Court so long as other government MPs such as Julia Banks join her.