The elevation of Jacinda Ardern to leader of the Labour Party caused a monumental shift in New Zealand's opinion polls.
From languishing in the mid-20% range, Labour is now within striking distance of overtaking National as the most preferred party to win the most seats in the September 23 election.
The poll of polls shows National still ahead and likely to win 57 seats, but the momentum started by Ms Ardern has Labour gaining.
It is something of a bitter-sweet feeling for Mr Robertson who challenged for the leadership in 2014 with Ms Ardern as his prospective deputy.
Now, Ms Ardern is leader and Te Tai Tokerau MP Kelvin Davis is the deputy; and he was nominated by Mr Robertson.
Asked if he had any regrets, Mr Robertson said anyone could see Ms Ardern was the right person to lead the party.
``She is intellectually very strong, displays empathy and has an capacity for detail. I knew she had the ability to step up to the role of leader. I am happy to be supportive of her. In a short time, this has been amazing to observe.
``Kelvin is a rural electorate MP, another part of us. And here I am, finance spokesman. I don't dwell on the past.''
Mr Robertson was in the South last week to first take part in the ASB finance debate in Queenstown and carry out support duties for candidates and MPs in the region.
On Friday, he caught up with Dunedin South MP Clare Curran and went canvassing out around his old stomping ground before attending a King's High School fundraising auction.
He told the Otago Daily Times he felt a bit out of place on the stage alongside illustrious old boys such as All Black Ben Smith and former All Black and All Black coach Laurie Mains.
When he was jokingly reminded he did play rugby in his youth, he admitted he was nowhere the standard of Smith and Mains.
The recent poll results had come as a surprise to most in Labour, including Mr Robertson.
``The latency was there in 2014 but the people were not ready for change. Now, people believe this is not as good as it gets. Jacinda has articulated that better than before.''
At the top level, the New Zealand economy was going well but on the level below, it was not so good, he said.
Inequality was rising, housing continued to be a major problem and productivity was low.
``The feeling I have is people are prepared to vote for change. But we have to build the trust.
``On the fourth time around, I am just as busy as ever. I am out there listening and enjoying the campaign. I do have a spring in my step.''
One thing had become clear since Labour's rise in the polls - people were much more interested in what Labour was saying, Mr Robertson said.
Apart from Ms Ardern, Mr Robertson has one of the heavier workloads of the Labour caucus, although he said MPs such as Dunedin North MP David Clark (health), Phil Twyford (housing) and Chris Hipkins (education) were also shouldering a heavy load on the campaign trail.
Mr Robertson is the Wellington Central MP and has 22 meet-the-candidates to attend, along with eight to 10 debates with Finance Minister Steven Joyce.
But he always has time to return to Dunedin and catch up on friends and family.
