KEY POINTS:
National MPs meet on Monday to elect a new leader, with the party's finance spokesman John Key frontrunner to replace Don Brash.
Dr Brash stepped down today after months of speculation that a caucus coup was imminent.
"The question of a change of leadership was a question of
when, not if, and I think that's become very destabilising for the party," he said at a press conference.
"I'm not putting my leadership on the line. I'm not saying vote for me or I'm out. I'm saying I will resign on Monday. Find another leader."
Dr Brash calmly explained he was not quitting because Nicky Hager's book on his leadership was about to be published, with information in it which Hager says will reveal dishonest dealings.
However, when he was no longer leader he would be in a better position to refute the "garbage" and "crap" that was in it, he said.
Dr Brash took National from 27 seats in Parliament to 48 at the last election, coming within a whisker of beating Labour.
But along the way he accumulated numerous gaffes in an accident-prone way that horrified his MPs.
Parliament was rife with rumours that the caucus was not going to let him lead the party through to 2008 because the risk factor was too high, and Mr Key was positioning himself for a challenge.
Dr Brash's dignified exit means there will not have to be a messy caucus coup, and that the new leader is likely to inherit a united team of MPs.
By tonight only Mr Key had put his hand up.
"I think I can bring to the job a fresh new dynamic and aspirational leadership for the party," he said.
"I think I represent modern New Zealand and the future of our country, while still embracing the values and principles of the party that served us so well over the years."
Mr Key said he would not be running on a joint ticket with a nominated deputy, and would leave that position up to the caucus to decide.
The present deputy leader, Gerry Brownlee, has strong support in caucus to run with Mr Key.
The only other MP with a chance of taking the leadership is Bill English, while Simon Power and Katherine Rich are considered remote possibilities.
National MPs gracefully accepted Dr Brash's resignation, and most praised him -- with one exception.
Rakaia MP Brian Connell, suspended from caucus after a series of clashes with Dr Brash, said "I feel very vindicated".
Deputy Prime Minister Michael Cullen delivered the Government's opinion.
"This continued instability in the National Party is a sign of a party still nowhere near ready to govern," he said.
"Dr Brash's resignation was inevitable. But it solves little."
- NZPA