The 70-year-old former National Party leader announced over the weekend that he wanted to step into Mr Hide's role to prevent the party being wiped out in the November 26 general election.
Dr Brash continued lobbying for the job yesterday, meeting Sir Roger Douglas and Hilary Calvert in Auckland to discuss his leadership bid.
He needs at least three of the party's five MPs to back him and has two of them -- Sir Roger and Heather Roy.
Deputy leader John Boscawen has said he supports Mr Hide and, until yesterday, Ms Calvert had said she was committed as well. However, following yesterday's meeting, Ms Calvert did not appear to be standing as firmly behind Mr Hide, refusing to comment on her position.
Dr Brash said this morning he was optimistic he had the support he needed, although Ms Calvert had not confirmed her support.
"I haven't heard that from her in so many words," he told Radio New Zealand.
"I expect that before she told me that she'd want to tell her own leader that."
Responding to reports Mr Hide could step down today, Dr Brash said it was certainly a possibility.
"If Hilary Calvert has in fact decided to back me that would be a logical thing for Rodney to do."
Dr Brash said there was merit in making a quick change, but that he was happy to wait until market research about his chances as leader came back next week.
"I've said to people who are dubious or not sure how to jump on this one, 'look, I'm very happy to wait for that research to be finished'," he said.
"I believe it was clear some weeks ago, indeed some months ago, that a party led by Rodney would not survive, whether a party led by me will, I don't know, but certainly in the last few days I've had overwhelming support."
Dr Brash said he had not heard back from Mr Hide since he left a message for him a few days ago.
Mr Hide yesterday posted an open letter on Facebook, saying he had been surprised by Dr Brash's weekend announcement that he was going to seek the leadership of ACT.
He said he had previously invited Dr Brash to join the party, and Dr Brash had turned him down.
"We reviewed various options on how we could work together in a collaborative way to build a strong party for the future," Mr Hide said.
"Don then wrote me a letter setting out his decision to turn down the opportunity. The letter alarmed me because I thought it was a letter designed to be leaked, as it was especially one-sided.
"My position is that I serve as leader of the ACT Party on behalf of the membership until the caucus and the board determine otherwise."
Prime Minister John Key has refused to speculate on the situation, although he said yesterday he could not see any reason why Mr Hide would not be able to keep his ministerial roles if Dr Brash took over as leader.
