New Zealand politicians are split on the prospect of Britain leaving the EU.
Act, NZ First and the Maori Party prefer a Brexit, but National, Labour, the Greens, United Future want Britain to remain in the union.
United Future leader Peter Dunne said he was strongly in favour of the "remain" camp, and said New Zealand would be "caught in the crossfire" of a Brexit.
After taking a surprise lead in polls a week ago, enthusiasm for the leave vote has slipped ahead of tomorrow's referendum.
NZ First leader Winston Peters attributed that change to the murder of British Labour MP Jo Cox. He said a Brexit was "our best chance to reverse the steady loss of access rights Kiwis have in the UK".
"Leave is our best bet to make the Commonwealth and the institutions we share strong and enduring."
But Green Party co-leader James Shaw said he would prefer a "remain" vote, as "the EU is generally a force for good in the world".
Act leader David Seymour contended bureaucracy of the EU had achieved very little and economic links would recover quickly following an exit and Kiwis' access to the UK could improve if migration from Europe was reduced.
Mr Key, who has said he would prefer it if the UK stayed in the EU, said that Britain would be unlikely to open its doors further to Kiwis if it leaves the EU.
Labour leader Andrew Little said Britain was one of New Zealand's biggest allies in the EU that would be lost if Brexit won.
A spokeswoman for Maori Party co-leader Marama Fox said her preference was for Britain to leave.
Where they stand
John Key, National.
Andrew Little, Labour.
James Shaw, Green Party.
Peter Dunne, United Future.
Winston Peters, NZ First.
David Seymour, Act.
Marama Fox, Maori Party.