National leader Simon Bridges says he's "done nothing wrong" after the National Caucus voted to expel Jami-Lee Ross from the party.
The rogue MP made a series of explosive corruption allegations about him in a surprise press conference, held on Tuesday morning while the Caucus met to discuss his future.
Among those claims was that Mr Bridges committed electoral fraud, an allegation he labelled "baseless". When directly questioned if he had asked Mr Ross to hide a donation of $100,000, Mr Bridges said "no".
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He told media there was "zero chance of having done anything illegal", and described Mr Ross as "a lone wolf" who is now "irrelevant, as far as we're concerned".
Mr Bridges also repeatedly invited police to investigate the claims against him.
"I entirely reject the allegations Jami-Lee has made around the handling of political donations," he said in a follow-up statement.
"I invite Jami-Lee Ross to take these matters to the police, and I invite the police to investigate them fully and promptly. They will find the allegations are baseless."
Mr Ross had earlier used his press conference to rubbish Mr Bridges' leadership and resign from the National Party. He announced he'd run as an independent candidate in a by-election in his electorate of Botany.
The scandalous back-and-forth between Mr Bridges and Mr Ross comes after an investigation into an expenses leak couldn't definitively identify the leaker, but pointed to Mr Ross.
Mr Ross vehemently denies the allegations, and cut across his leader's big announcement by taking to Twitter five minutes beforehand to make allegations of his own.