Don Brash, who formally resigned as leader at a party board meeting last night, has taken responsibility for the woeful result. But he also cited a damaged brand from the past term that was defined by caucus infighting and scandals.
The party has now committed to a full review that could result in a restructure and a new party brand and name. The party will also search for a new leader. Mr Banks appeared to endorse former party president Catherine Isaac as a leader outside Parliament, but Ms Isaac ruled that out yesterday. That leaves Mr Banks, who won the Epsom seat and who has not ruled out the leadership, as the leading contender.
Party president Chris Simmons said the review would consider how to position itself while retaining the principles of freedom, choice and personal responsibility. The review may change the party brand within 12 months.
But questions remain over the party's future and long-term survival.
Ms Isaac said the future depended on Mr Banks. "Will John Banks embrace Act ideology and its policies and seek to advance them?
"I don't know how John Banks is planning on conducting himself. His history is with the National Party, not with Act, and I don't know to what extent he embraces Act principles."
She said she did not intend to take an active role in the party, but there was a future for a classical liberal party.
Mr Banks' conservative views have rubbed the more socially liberal Act members the wrong way. But he was comfortable because of what he called the "80/20" principle - he agrees with 80 per cent of the party's policies.
Dr Brash said he was disappointed at the election result and would take time to consider his future.