Protesters are targeting the Young Nats Ball.
Auckland Action Against Poverty says it'll protest outside the event at the Heritage Hotel in Auckland tonight.
"The Young Nats are celebrating while the policies of the National Party continue to wage a war on the poor," says the group's spokeswoman Sophie Morgan.
The group targeted a National Party Christmas function in Auckland in December, preventing Prime Minister John Key from attending.
He later labelled them as thugs and bullies.
The ball is being held in the Grand Tearoom of the hotel, according to a post on the NZ Young Nats Facebook page.
"Don't miss the chance to get glammed up and rub shoulders with the leaders of the country," the webpage advertising the event says.
The dress code is black, or National Party blue, tie.