Greens co-leader James Shaw has accused National of calling for the election to be delayed out of concern for their own self-interest, not democracy.
National leader Judith Collins wants the prime minister to postpone the election until late November, or preferably next year.
"We are a first-world liberal democracy where people expect to be able to cast their vote and if we can't think of ways to do it properly then we need to delay the election ... if it's just a postal vote, then no - that's not good enough", she said.
However Shaw said Collins' concerns were purely political.
"National are relying on the economy to get weaker ... and so the later the election is, the more likely, in their view, that the economy will suffer and that therefore their political fortunes will rise," he said.
Shaw said any decision regarding the election date should be made by the Electoral Commission.
"They were given additional funding to be able to run an election with the country at level 2 and parts of it at level 3 and I really think it should be their call.
"If their advice to the prime minister is, look, we think that turnout or viability is at risk, that is the point at which the election should shift."
Shaw said moving the election to a date in October or November, or even next year, did not provide any more certainty as there was always the risk there would be another outbreak.
New Zealand First leader Winston Peters said now was not the time to be thinking about the election date, and the focus needed to be on "health first, politics second".
"The general election and the campaign that precedes it needs to be free and fair for all concerned - parties, candidates, officials, and most of all voters.
"If that means delay then so be it. But that is for another day. Today we need our team of five million mobilised once more to play their part so New Zealand can recover its previous health position," Peters said.