Act opposes the legislation and Seymour thinks the new National leader, who will be elected on Tuesday, should take up the party's suggestions to improve the bill, which will give effect to the new housing plan.
"We have suggested, through the select committee that they could, first of all, have an extension of time because one of the aspects of this dirty deal with the red devil which is it's rushed through under cover of Covid before Christmas," Seymour said - pointing to the fact the bill has been forced through a truncated select committee process.
Seymour acknowledged that National pulling out of the agreement would accomplish little, given Labour's clear Parliamentary majority.
But he said National could use its position as part of the accord, to negotiate different legislation.
"They could ask for it to be made an omnibus bill in order that infrastructure funding could be added to it, that again is something we have advocated and are asking for in the bill," Seymour said.
Councils have complained the bill will increase infrastructure costs, although this claim is disputed.
Infrastructure Commission economist Peter Nunns, who submitted on the bill, disagreed that the bill would put up the cost of infrastructure.
"The reason for that is the primary impact of the bill will be to give others the opportunity to build homes and give opportunities for growth in urban areas rather than increasing - significantly increasing - the total population that needs to be serviced with infrastructure," Nunns said.
However, Nunns and a number of councils argued that even before the bill councils had been struggling to keep up with the cost of new infrastructure. Councils have long argued that new tools are needed.
Seymour also said the Government could dump the new "Medium density residential standard", which allows much of the densification, "at least in Auckland" and go back to the "mixed housing urban" zoning.
The Government's analysis of the mixed housing urban zone's effectiveness found that while three story buildings could be built in that zone "would have a more limited impact on development capacity and therefore housing supply", because other standards in that zone meant "in most cases three storeys cannot be built".
Seymour is currently more popular than former National leader Judith Collins and both Chris Luxon and Simon Bridges, the two people racing to replace her. In four recent polls he's performed better than all three as preferred prime minister, however National's polling has continued to be higher than Act's.
Seymour also said the new National leader should take a stronger stand on climate change.
He said the new leader should commit to repealing the Zero Carbon Act, the legislation that establishes the Climate Change Commission and New Zealand's emissions reduction regime.
"We should simply tie New Zealand's emissions to our trading partners' by capping the ETS at that level, and allow free trade within it, rather than trying to tell people what kind of car to buy and how to cook their steak."
