"Game, set and match to National. Labour can't win this election.

Jacinda Ardern can develop into the role of leader, she's got what it takes in the long term, but the mountain is too steep to climb right now."

That's what I said on-air verbatim exactly one month ago today. I was hosting the drive show on the day that Jacinda Ardern took over the Labour leadership on August 1st. 

She was holding on the line listening to my editorial, and waiting to be interviewed. 

This is how Ardern responded to me. 

"I do not accept the somewhat bleak editorial that you just gave Rachel, but I do expect that over the next seven and a half weeks, and it's only right that this happens, that I will be put through my paces. That Labour will be questioned about the vision that we have for New Zealand. That's what election campaigns are all about." ​

Well, Ardern was right. And I was wrong. 

Could I have been any more wrong? I wrote them off. Not a chance, I said. But iI said they'd be in good shape to challenge for government in three years time. 

Ardern one. Smalley nil. 

And then last night, well.....what a night. 

First, the poll. The Colmar Brunton poll on One News. I was nipping around in the kitchen trying to sort dinner and I had the news streaming in the background on my laptop.  Finn was hungry, I had a cat squawking at me to feed it as well....and then I heard it. The top story.  And it stopped me in my tracks. 

Labour is the now the largest party in parliament. Labour is the front-runner to form the next government. 

Really? Labour is ahead of National? Really? 

And then came the preferred Prime Minister poll. And Jacinda Ardern has had a blinder. She's leapt ahead of Bill English. She's on 44 percent, that's one percent ahead of English. 

What a turnaround. What a turnaround with just three weeks to go until the election. 

And then, of course, came the debate. 

Ardern looked nervous at the start. But she settled. But I don't think Bill English ever did. At times he looked rattled and uncomfortable. And Ardern grew in confidence. 

Some of her one-liners, particularly around housing, stopped the Prime Minister in his tracks. 

At one point she said "Bill, tell someone in Auckland that $150,000 is acceptable as a deposit. It's not...." and the Prime Minister had no response. 

Predictably, English targeted labour's rather vague and undefined tax policy, and the capital gains tax. 

Ardern's response? "A capital gains tax doesn't strike fear in people who have no hope of owning a home. I'm doing this so my generation can get into the housing market." again, no response from English. 

She won last night's debate but not overwhelmingly. 

English, I think, was rattled by that poll result. This is National's election to lose. And given John Key's overwhelming dominance in the polls over the course of the last 8 years or so, you've got to ask what's changed. Well, it's the leadership. And English knows this is on his shoulders. 

But even the boldest of political commentators could never have predicted this. Just three weeks out from a general election, and Labour, under Jacinda Ardern, is the front-runner to form the next government.

What a turn around. What an election campaign. Buckle up, people. Who says politics is boring?