With the election just weeks away the tweet immediately drew a flurry of responses with calls for Morgan to apologise.
Many accused the TOP leader of crossing the line and showing a high level of disrespect.
The tweet was variously described as terrible, misogynistic, horrendous, despicable and unacceptable to refer to a successful woman as lipstick on a pig.
He was also accused of "Kiwi bloke" casual sexism that tapped into a Trump-style alt-rhetoric to appeal to apathetic voters.
An unrepentant Morgan took to twitter this morning saying the pig he was referring to was the "Estab Party" that caused the rise of inequality and had done nothing since addressing the problem.
It needed more than infatuation with Ardern to solve, he posted.
He later encouraged people upset with his comments to focus on policy discussion and rather than "sideline chatter" and posted a photo of a used lipstick sitting next to a toby jug of former Prime Minister Sir Robert Muldoon.
But that has done little to assauge many of his detractors with even his own support base taking him to task.
Poster Mark, who identified himself as a member of TOP, told him it was a mistake to make the lipstick comment about Ardern and to "man up and apologise".
Herald columnist and singer Lizzie Marvelly lashed out, saying Morgan needed to show he was more than a "sexist old dude who hurled unfortunate ad hominem attacks at his opponents".
Marvelly, who was at yesterday's Labour Party campaign launch in Auckland, said the Twitter spat had both the leader and the party's press officer scoring own goals, left, right and centre.
"What a class act," she posted followed by the word sarcasm.
Others on Twitter posted this would even threaten to cost TOP the chance of their vote.
TOP spokesman Sean Plunket said the tweet was a euphemism to show the Labour Party had only made a cosmetic change.
"I mean, Barack Obama used it on Sarah Palin in 2008."
Obama used the phrase at a campaign rally in 2008, while saying opponent John McCain's policies were no different from George W Bush's.
Some in the Republican camp argued it was actually an attack on McCain's running mate Sarah Palin.
Plunket said there would be a press conference later this morning to clarify Morgan's twitter comments.
"The people who are upset about this are also the people who thought Metiria Turei was the second coming of Christ.
"We've not lost any of our voters."
Plunket had earlier tweeted: "It's not a sexist comment it is a euphimism, like selling someone a false bill of goods. So calm the farm."
He later responded to further criticism: "Oh ffs be offended then it's clearly what you want."
Ardern has been approached for comment. A spokesperson said she would likely address the issue at this morning's press conference in Tauranga.
