The Labour Party's seeing an unprecedented groundswell of support since Jacinda Arden took the reins of the party yesterday.

$250,000 has been donated to the party since midday on Tuesday and 1000 people had signed up as volunteers by midday on Wednesday. $150,000 was donated online and $100,000 offline.

Labour's Campaign Manager Andrew Kirton says the party has never seen anything like this.

"We've had a fantastic response, pretty much the minute Jacinda was announced as our new leader," he told Newsub.

"People have been donating online...made up of mums and dads and ordinary folk giving an average of about $30 each. We've never encountered that before and it's something pretty extraordinary for us."

Mr Kirton says donations peaked at 12:31pm yesterday - just minutes after Ms Ardern began her first official press conference as Labour leader.

"Almost half of those people that have given some money online - we've never heard from before."

"People are really attracted to someone that is positive, that's got real energy, that's got youth and has real things to say about the future of New Zealand."

But Mr Kirton says the party will need a lot more money to fight its campaign, calling the National Party a "juggernaut".

Newshub.