New Zealand First leader Winston Peters has called for the election to be delayed until November 21, citing the resurgence of Covid-19 in New Zealand.
It comes after Opposition leader Judith Collins on Wednesday called for a delay in the election to November or next year.
Ms Collins said if the threat of Covid-19 was still in the country come November, Ms Ardern should call back Parliament and by majority could have the election next year.
“We think that that is probably the better alternative,” she said.
In a statement released today, Mr Peters said the Government's health response must come before politics.
"Since Monday evening, August 10, we have said that our health response must come first and politics second. That remains our view as the case numbers rise each day," Mr Peters said.
Mr Peters claimed the "likely source of the outbreak" could be traced back to the border, adding that the current cases are not linked to a unique strain of the virus and "the Americold connection does not exist, as product from that source has not been imported into the country for months".
"There is now no ability to conduct a free and fair election if the Prime Minister decides to hold the General Election on September 19," he said.
"If September 19 is confirmed political parties will have only six days to campaign before overseas voting begins on September 2 and nine days before advance voting begins."
Mr Peters said only 44 per cent of votes at the 2017 General Election were cast on Election Day.
NZ First has since voiced "real concerns" around the "state of preparedness of the Electoral Commission and our postal service" to process an "unprecedented deluge of special votes".
"Any proposed staggering of their vote in the election across several weeks is a weakening of and serious interference in our democracy.
"Voters would be asked by government to exercise their franchise with different levels of information from each other and that is unacceptable."
Mr Peters said allowing the election to operate in Auckland under Alert Level 2 has also raised concerns around voter turnout, calling the playing field "hopelessly compromised".
"The psychology of Auckland voters, as well as the wider voting community, is highly likely to lead to a reduced turnout given legitimately held health fears; by how much is the real concern.
"Voters need to be able to hear from all political parties about their Covid response and other policies. That is fair. But until Auckland’s alert level comes down the playing field is hopelessly compromised."
NZ First first came forward to Prime Minister Jacinda Ardern with a letter stating their concerns on August 14, released today, citing fears the Covid outbreak was "compromising our ability to hold a free and fair election on September 19".
The party has since spoken to Ms Ardern about the party's belief it risks "undermining the legitimacy of the election result" and "creating an awful precedent which could be abused by the Prime Minister’s successors".
“People will be driven to the conclusion, in the absence of any empirical evidence to the contrary, that the election date choice is being forced from a minority position to achieve a certain outcome.
“This is a most regrettable yet avoidable situation. We are here as Members of Parliament first and foremost, not just as members of political parties."
In a statement, a spokesperson for Ms Ardern said the Prime Minister "has proactively sought the views of the leaders of every political party represented in parliament this afternoon about the election date".
"A range of views have been expressed that the Prime Minister has taken on board," the spokesperson said.
"The Prime Minister will provide an update tomorrow morning once she has also reviewed the most up to date health information on the situation in Auckland."