National is still deciding whether it will support the Zero Carbon Bill's second reading, despite reports Judith Collins' plans to vote against the legislation.
But National Leader Simon Bridges has joked that he would find out about what the senior National MP would do in "her memoirs".
This is a reference to the book Collins last week revealed she was writing about her time in politics.
The party supported the bill in the first reading but did not promise to throw its weight behind the legislation when it comes before the House a second time.
National Leader Simon Bridges said although there are major parts of the bill the party does not support, such as the methane reduction targets, the caucus has not yet landed on a decision.