The public campaign to legalise euthanasia had a rocky start with a lone protester attempting to derail the launch.
A handful of National MPs also fired a broadside against the End Of Life Choice bill, with senior MP Maggie Barry calling it "a license to kill".
ACT Party leader David Seymour this afternoon kicked off his campaign to win support for his member's bill which is set to be debated either tomorrow or early next year.
For all MPs - except those in New Zealand First - it will be a conscience vote which means they are not bound to vote with their party.
Mr Seymour said he was confident he had the numbers to get the bill past the first hurdle.
"We have a majority that is comfortable, but we're still working on people that are undecided to increase it."
He said MPs were coming to reflect the views of New Zealanders.
Mr Seymour was joined at the launch by Matt Vickers, whose wife Lecretia Seales died while fighting in the courts for the right to end her life.
Mr Vickers celebrated the bill's arrival and urged MPs to back it.
"Lecretia would be really excited to see this ... her ultimate goal was to get legislative change.
"So she'd be very happy to see that this was going ahead."
In support of the bill at the launch was Labour MP and Minister Iain Lees-Galloway, Green Party leader James Shaw and National MPs Nikki Kaye and Chris Bishop.
New Zealand First MPs will support the bill at its first reading, but want a public referendum before backing it any further.
Lone protester Russell Franklin attempted to disrupt the launch, shouting questions at Mr Seymour while he addressed reporters.
Dr Franklin, a retired paediatrician, said the legislation would take the country "back to the era of Nazi Germany".
MPs across the house are divided.
Prime Minister Jacinda Ardern said she'd be supporting the proposed law in line with her long-held position.
"I will always look for safeguards in place to make sure that noone is ever manipulated or left vulnerable.
"But I also support people having their own choice in those circumstances."
But National leader Bill English said it was "a very bad piece of legislation" and he would strongly oppose it.
"We've just been through a big discussion about suicide in New Zealand," he said.
"It's going to be a bit tricky for Mr Seymour to answer the question as to why some suicides are good and some are bad."
On her way into a caucus meeting this morning, National MP Maggie Barry called the legislation "a license to kill".
"It has no protections and provisions for the disabled, the elderly and the vulnerable. It would make us the most liberal country in the world to die."
Her colleague Michael Woodhouse also spoke out.
"I have a strong view that we don't kill people.
"Even if you are of a mind to support the bill, I think it's terribly written."
New National MP Simeon Brown said the bill had no safeguards and threatened to "open up the floodgates".
"In its current form, it's the worst piece of euthanasia legislation I've seen in the developed world."
Mr Seymour said the objections were "disingenuous".
"This has got stronger safeguards than any other bill that's come before New Zealand's Parliament.
"At any given time 98-99 per cent of people don't have a terminal illness or a degenerative condition and so aren't qualified.
"You have to be in an advanced state of decline."
Mr Seymour is holding a briefing tonight for undecided MPs to discuss the evidence and address their concerns.
How will MPs vote at first reading - a sample
Yes: Jacinda Ardern, Kelvin Davis, Grant Robertson, Megan Woods, Andrew Little, Nanaia Mahuta, Stuart Nash, Iain Lees-Galloway, Clare Curran, Kris Faafoi, Peeni Henare, Michael Wood, Adrian Rurawhe, Deborah Russell, Ginny Andersen, Louisa Wall, Paul Eagle, Raymond Huo, Ruth Dyson, Trevor Mallard
No: Phil Twyford, Aupito Su'a William Sio, Rino Tirikatene
Undecided: Carmel Sepuloni, David Clark, David Parker, Damien O'Connor, Liz Craig, Willie Jackson, Willow-Jean Prime
New Zealand First
Yes: Winston Peters, Ron Mark, Fletcher Tabuteau, Tracey Martin, Darroch Ball, Clayton Mitchell, Mark Patterson, Shane Jones, Jenny Marcroft
Yes: James Shaw, Eugenie Sage
Yes: Nathan Guy, Nikki Kaye, Mark Mitchell, Jami-Lee Ross, Matt Doocey, Brett Hudson, Chris Bishop, Matt King, Andrew Falloon
No: Bill English, Gerry Brownlee, Christopher Finlayson, Michael Woodhouse, Todd McClay, Maggie Barry, Parmjeet Parmar, Simon O'Connor, Sarah Dowie, Todd Muller, Shane Reti, Alastair Scott, Simeon Brown, Chris Penk, Lawrence Yule
Undecided: Steven Joyce, Simon Bridges, Amy Adams, Jonathan Coleman, Anne Tolley, Nick Smith, Paul Goldsmith, Louise Upston, Alfred Ngaro, Nicky Wagner, Jacqui Dean, David Bennett, Tim Macindoe, Scott Simpson, Barbara Kuriger, Melissa Lee, Nuk Korako, Stuart Smith