Kelvin Davis also says he would give up the role of deputy prime minister to Winston Peters, after National's Paula Bennett said the same today.
Labour's deputy leader was slightly more reluctant in his wording than Ms Bennett though, saying it wasn't a decision that would be taken lightly.
"It's not something we would give up lightly," Mr Davis said while addressing media with Jacinda Ardern this afternoon.
Mr Davis said he was ready to give up the role if it meant his leader would become prime minister.
"My priority is to make sure Jacinda Ardern is the prime minister and if it has to be, it has to be," Mr Davis said.
Earlier in the day National MP Paula Bennett also appeared more than happy to give up the role to Mr Peters.
"I'm not too bothered to be honest, I love what I do and I'd still be deputy leader of the party.
"That's the main thing really, we will just work our way through it," Ms Bennett said.
Ms Ardern also announced that she would be leading negotiations with Mr Davis, a close friend of the New Zealand First leader, when it comes to trying to form a coalition government.
No final deal is expected to be made until the special votes result is announced on October 7.