Eight Labour members have quit the party in protest over a proposed electorate deal with the Greens in Nelson.
It includes one supporter who held membership for 30 years and the campaign's coordinator is also understood to have walked away.
One of those who quit said the members had emailed in their resignations - and the reasons - to the party.
"They were eight core people and they've walked away. They expected us to help the Greens… we're not going to work for the Greens, bugger that."
The ex-member said supporters were unhappy about how they learned about the proposed deal.
"It leaked out at the [annual] conference. One of the candidates was told by Andrew Little… people here are really angry.
"It doesn't make any sense, the numbers don't stack up. NZ First will just suck up all our numbers."
Labour's general secretary Andrew Kirton said: "There isn't an agreement in Nelson.
"We've had a couple of resignations but nothing different to the usual flow of members coming and going across the country.
"Labour is strong in Nelson and I've been impressed by how our members have remained committed to winning government next year, while understanding you can't give a running commentary while discussions take place."
National's Nick Smith has held the Nelson seat since 1996.