"If you said to me the day after the election, 'you'll start the election year with polling numbers that vary between 35 and 38 and you'll be consistently on average ahead of National' ... I would have taken that in the heartbeat," Mr Hipkins told AAP last month.
Bombshell claims from Mr Hipkins' ex-wife this week have changed all that, with Mr Hipkins even considering quitting politics.
On Sunday, Jade Paul - who was married to Mr Hipkins for two years and with whom he shares two children - posted a series of attacks on the 47-year-old on social media.
Mr Hipkins has categorically denied the claims, which portray him as a poor husband and father during times of her extreme distress.
"I reject the allegations that she's made and the characterisation of those events," he said at a press conference on Tuesday.
"I'm not going to litigate the details of any of those things publicly, I don't think that's in anyone's best interest ... particularly not for my children."
Mr Hipkins became tearful when asked if it had affected his children, which he could not speak to, as they were on holiday with Ms Paul.
Fronting up for his weekly interviews on Wednesday, Mr Hipkins said he'd thought of throwing in the towel.
"It would be untrue to say that those thoughts hadn't crossed my mind in the last 48 hours," he said.
"But everybody in their lives at some point goes through rough patches, and you just have to keep getting out of bed every day."
It remains to be seen whether Ms Paul will continue attacks on her former partner on the road to the November 7 election.
Muddying the waters, Ms Paul has worked in a ministerial office of NZ First - one of Labour's opponents - since their separation.
The unedifying episode has provoked discussions on the private lives of politicians, and what the public has a right to know.
Mr Hipkins - prime minister for nine months in 2023 following Jacinda Ardern's resignation - has kept his children out of the public eye, excluding them from campaigning or social media.
The Wellington-based MP has, however, a high-profile new relationship, which he announced on election night in 2023 by thanking Toni Grace in his concession speech.
"I didn't intend to do it that way, but it just sort of happened. That's what happens when you do a off the cuff remarks at the end of a speech," he told AAP.
Mr Hipkins proposed in November on Ms Grace's 40th birthday, and told AAP there were plans for a 2027 wedding.
"We're thinking sometime after the peak of summer next year, just because the late summer period is just really frantic on the political calendar," he said.
That would mean Mr Hipkins - should he win the next election - would become the first Kiwi prime minister to tie the knot while in office.
That possibility may have been dented by Ms Paul's claims, which remain largely unreported by mainstream outlets but circulate on social media.
Opposition parties are not seeking to highlight the matter.
"I'm staying right out of it," Police Minister Mark Mitchell told Newstalk ZB, "he can deal with it".
Labour's police spokeswoman Ginny Andersen said her party room was standing by their leader.
"We're 100 per cent behind him and we've all messaged him over the last 24 hours to show our support," she said.
New Zealand's top-rated broadcaster Mike Hosking, an opponent of Labour, suggested Kiwi MPs deserved to keep their private lives private.
"You could argue Hipkins and his ex represent a large slice of the New Zealand countryside: married, divorced, things got messy - that's life experience," he said.
"What a mix - public life, social media, gossip, innuendo, anger, broken hearts, revenge, toxicity, and sticky beak-ery.
"Who would be an MP?"
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