National Party leadership battle is 'very close' - Michelle Boag

The battle to take the leadership of the National Party has come down to a two-horse race, a former president for the party says.

Speaking to The AM Show on Tuesday, Michelle Boag said there are only two real contenders.

"It's going to be very close but I think it hasn't changed from the outset," she says.

"It's either going to be Simon Bridges or Amy Adams... certainly [Judith] Collins, [Mark] Mitchell, [Steven] Joyce will be the ones that drop off first."

The party's 56-member caucus will meet at 10:30am on Tuesday, and the five candidates will get their last chance to pitch for the job ahead of a secret ballot.

No one is likely to get the 29 votes needed to win on the first ballot. The lowest-polling contender will drop out and voting goes on until one of them has the support of a majority of caucus members.

"I understand it is very close, very unlikely to be a first ballot decision," Ms Boag says.

"There will be people who are voting strategically for someone who they know won't win but they might be supporting them for other reasons - long-term profile etcetera."

Ms Boag says there needs to be a gender balance in the leadership - so if Mr Bridges wins Paula Bennett is likely to continue as deputy. If Ms Adams wins, then Mr Joyce is likely to replace Ms Bennett.

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