Barnaby Joyce should stand aside as deputy prime minister and not have his vote counted in parliament amid doubts about his eligibility, Labor says.
Opposition frontbencher Tony Burke told MPs the lower house was "breaking new ground" by referring a government MP to the High Court to see whether the Nationals leader was validly elected following revelations he could be a citizen of New Zealand.
The court was effectively being asked to decide whether the Turnbull government had a legitimate parliamentary majority, he said.
Mr Burke suggested if the coalition had "any level of principle" Mr Joyce would stand aside and the government wouldn't accept his vote.
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He noted Nationals senator Matt Canavan had stood aside from his cabinet position given the uncertainty around his citizenship status, and questioned why Mr Joyce hadn't done the same.
Leader of the House Christopher Pyne said it was time for the High Court to give a clear ruling on what section 44 of the constitution - which bans dual citizens from sitting in parliament - means.
He insisted Mr Joyce had acted ethically and correctly and took immediate action when concerns were raised.
