Meanwhile, Colin Craig agreed to end a confidentiality agreement signed with former press secretary Rachel MacGregor, which could lead to the disclosure of embarrassing details including romantic poems.
Mr Craig said yesterday the Conservative Party board was likely to dissolve and a membership vote would be held to choose the next leader.
"The party still has a future," he told the Herald. "This is a really good watershed and I think good things will come out of it."
Others were more sceptical.
Mrs Rankin said Mr Craig had learned little from the debacle.
"This political party set itself up as being different," she said. "You can't be the leader of that and say you are above others in terms of your behaviour."
She said the final straw was Mr Craig's "excruciating and embarrassing" press conference on Monday, when he revealed inappropriate interactions between him and Ms MacGregor but rejected claims of sexual harassment.
The details of these interactions have mostly been suppressed by a confidentiality agreement signed between the two.
Mr Craig said he was happy to lift the lid on the agreement. Ms McGregor, who wanted to speak publicly about the events which prompted her departure from the party, did not respond.
Mr Craig's answers to questioning indicated the interactions were more emotional than sexual. Party insiders have suggested Mr Craig liked Ms MacGregor tending to his hair.
It has also been alleged Mr Craig wrote romantic poetry to his former staffer.
Mr Craig refused to discuss an alleged poem, saying he was still bound by the confidentiality agreement.
One person likely to benefit from the Conservatives' collapse is New Zealand First leader Winston Peters, whose party shares a similar voter base.
Few survivors on this political train wreck
To liken yesterday's mass resignations from the board of the Conservative Party to rats jumping from a sinking ship would be unfair. Unfair to rats, that is.
So much for solidarity. So much for the board being adamant that Colin Craig had to be dumped as leader and the party quarantined from his mistakes and misdemeanours.
So much for all the humbug about principle and upholding high standards. From the moment Craig put the heat on the board by indicating he would not be going without making an unholy battle of it, the board's stoicism began to melt. Forget speed-dating. In the Conservatives' case, speed divorcing seems more the natural order.
Clearly, the question of how best to relegate the party's founder and principal benefactor to irrelevancy split the board.
That much could be deduced from the rift between the chairman, Brian Dobbs, and board member, John Stringer. The latter has behaved in a highly unorthodox fashion by providing a running commentary in the media about the events since Craig stood down as leader.
Dobbs yesterday threatened Stringer with suspension from the party for making confidential information public without authority.
As of last night, Dobbs and Stringer were among the last men standing.
But yesterday's board meltdown had an inevitability about it. At the risk of sounding like a cracked record, Craig is the Conservative Party and the Conservative Party is Craig.
Without him, the party amounts to little more than a political sect. It is now a political train wreck.
Support for the Conservatives, who just fell short of picking up 100,000 votes at last year's election, will have gone into free-fall.
Unless voters belong in the category of impossible-to-shift core supporters of one or other of the major parties, they apply a simple test when it comes to ticking the ballot paper: if a party cannot run itself properly, then there cannot be much hope of it running the country properly.
Because minor parties have scant loyal voters, they get punished more heavily than National and Labour. To the long list of minor parties which have found themselves on the wrong end of voters' venom - the Alliance, United Future, Act, Internet Mana - add the Conservative Party. For the time being , at least.
