Labour Party President Nigel Haworth says the National Party is still grieving about losing power after the 2017 election.
"Their sense of entitlement is on full display," he told the Labour conference in Dunedin this morning.
"Cornered creatures attack and they attack fiercely - so it will be with National.
"They will do what they will to regain power.
"National is still grieving about the loss that they faced and that they still manifest a view that somehow they were cheated, that somehow something happened that wasn't fair, wasn't reasonable and they are clearly fighting very hard to come back to power."
Labour's task was simple, he told delegates.
"Do not rise to National's excesses. Focus on the tasks that build the party vote in 2020. Build on today's excitement and pride in all we do in our daily lives."
He raised the possibility of having to face a byelection - although he did not explicitly mention Jami-Lee Ross' Botany seat.
He said preparations for the 2020 election were well underway.
The party's New Zealand Council had signed off plans for the next two years and fundraising was gearing up for a big new push in February.
The party's current financial situation was sound - "as sound as it has been in years, but we have to do better."
He also said the party was developing a modern health and safety regime for the party as a whole.
"Within that regime we are placing special emphasis on the creation of a safe environment in which bullying and harassment have no place.
"This is an especially challenging task in a volunteer-based organisation, and we are asking specialist organisations to share their expertise with us."
The conference was a place for celebration. But members should not be angry.
"National is well-resourced and angry."
The conference heard speeches this morning from deputy leader Kelvin Davis, Council of Trade Unions Sam Huggard, and E Tu union member and pay equity campaigner Kristine Bartlett.