Don Brash looks certain to become Act's new leader after the party's newest MP, Hilary Calvert, switched sides yesterday following a private meeting in Dr Brash's Auckland apartment.
A vote could be held at the next caucus meeting on Tuesday, but if Mr Hide accepts he has lost majority support to the former National Party leader, he could resign earlier to make a more dignified exit.
The Act board is to meet on Saturday morning in Auckland, and if Mr Hide has not resigned by then, that could be the logical place for him to accept defeat.
It is most likely he would stay in Parliament and not force a byelection, but it is not known if he would remain as an Act MP or become the independent member for Epsom.
Dr Brash would become leader outside Parliament.
Prime Minister John Key said from London yesterday that if Mr Hide were rolled as leader, he would be able to keep his ministerial posts - Local Government, Regulatory Reform and Associate Education.
Dr Brash hosted Ms Calvert and Act founder Sir Roger Douglas together yesterday.
The Herald understands Ms Calvert - whose vote is the key in a caucus decision on the leadership - has switched from unequivocally backing Mr Hide to supporting Dr Brash.
One of the issues they discussed was Dr Brash's position on the Treaty of Waitangi and Maori issues.
Dr Brash said last night that he and Ms Calvert, who was a vociferous opponent of the foreshore and seabed legislation, saw eye to eye on those issues.
The extraordinary events of the past week have played out in public since Dr Brash revealed his wish to take over the leadership of Act and threatened to set up his own right-wing party if his bid failed.
Hilary Calvert, a Dunedin lawyer, entered Parliament in September last year when MP David Garrett quit in disgrace after revelations that he had committed identity theft and had an assault conviction.
On Sunday, she said that she backed Mr Hide and would vote for him over Dr Brash, and on Tuesday she repeated that position.
But yesterday, when the Herald asked if her position was still the same after her meeting with Dr Brash, she said: "I'm not prepared to make any comment."
Sir Roger and MP Heather Roy have been firmly in the Brash camp, having had clashes with Mr Hide over his leadership style.
Ms Calvert's vote would give Dr Brash a 3-2 majority to become leader.
Last night, Mr Hide said he did not know if he had majority support in caucus.
"The caucus and the board need to make their own decision ... What I've always done is accepted that I'm the leader while I have the support of the caucus and the board," he told Campbell Live.
Even if he knew he had the numbers, he said, he would not proclaim victory as he was not that arrogant, "because I serve at the pleasure of the party".
If he was rolled, Mr Hide said, he would continue to "support John Key and work to honour the confidence and supply agreement".
"But Don Brash has been very clear about my future ... He said there's no room for me in Parliament."
Dr Brash several times referred to Act as though he already belonged to the party.
"If I can't get 5 per cent [of the vote] I shouldn't be trying to do this ... We should be getting much more than 5 per cent."
Asked why people should vote for Act in Epsom when he was so critical of National, he said: "We are the only party in Parliament which is even remotely akin to what National stands for."
Dr Brash reiterated yesterday that he would like to see John Banks, former Auckland City mayor and National Party Cabinet minister, stand for Act in Epsom.
Dr Brash told the Herald he personally would better serve the party by gathering support throughout the country rather than being beholden to an electorate, although he probably would stand in an electorate seat.
Once it is clear that Dr Brash has the numbers, he is expected to apply for membership of the Act Party.
Party president Chris Simmons has said the board is unlikely to oppose the caucus choice of leader, even though it can do so.
- Additional reporting: Nicholas Jones
* DON BRASH
A former Reserve Bank Governor, he has been repeatedly wooed by Rodney Hide as a potential deputy or co-leader of Act.
He was elected to Parliament in 2002, and became National Party leader in 2003.
He came within a whisker of winning the 2005 election for the National Party, but resigned in 2006 after John Key became party leader.
* RODNEY HIDE
Elected a list MP in 1996, became Act leader in 2004 and has been the MP for Epsom since winning the seat in 2005.
He won the seat again in 2008, but has lost popularity after a series of scandals that hit him and the party in the past 18 months.
These included using taxpayer-funded travel perks to take his girlfriend - now wife - overseas, his falling-out with Heather Roy and the resignation of MP David Garrett after an identity-theft offence was revealed.
* HILARY CALVERT SAYS
Supported Rodney Hide and would vote for him over Don Brash.
Reconfirmed what she said on Sunday.
No comment, after meeting Brash.