The Free Speech Coalition is offering its support for US whistleblower Chelsea Manning to speak in New Zealand.
"The political whims of the National Party must not curtail our right to engage in the most relevant topics of our age," spokesperson Chris Trotter said.
The National Party says Ms Manning should not be allowed into the country because she had a criminal conviction, but the coalition has asked the party to reconsider.
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"The subject of our allies' wartime conduct is a matter of great public importance," Mr Trotter said.
"As a democracy, we have a right to be informed on the activities of our friends on the international stage. New Zealanders deserve a chance to hear her speak."
Ms Manning, a former US Army intelligence analyst, was found guilty of espionage and theft and sentenced to 35 years in prison for leaking military files to Wikileaks.
Her sentence was commuted by President Barack Obama and she was released from prison in May 2017, following a tumultuous seven years behind bars which included two suicide attempts and a hunger strike.
She plans to speak about her time in prison, privacy, transgender issues and Wikileaks.
Mr Trotter said examples of convicted criminals that were allowed into New Zealand included Nelson Mandela in 1995, and Jordan Belfort, also known as the 'Wolf of Wall Street', in 2014.
The coalition says it supports Green defence spokesperson Golriz Ghahraman, who has spoken strongly in favour of Ms Manning.
"This isn't an issue of defending breach of confidence or leaking military secrets. Rather, it is the right of New Zealanders to hear from someone who is noteworthy albeit controversial," Mr Trotter said.
The coalition was formed after far-right speakers Lauren Southern and Stefan Molyneux were refused council venues for their speaking tour of New Zealand.
Immigration New Zealand is currently considering Ms Manning's request for special direction to be granted a visa. If that is not successful, she will also be able to approach the Minister or Associate Minister of Immigration.