Labour got in first for talks with NZ First this morning, with NZ First meeting with National in the afternoon.
NZ First leader Winston Peters has repeatedly said he is tracking well to meet his self-imposed deadline of Thursday for a decision on which Government he will back.
Leaders of Labour and National have both been spoken positively of the talks, but have closely guarded the specific topics of discussion.
Refresh the page for the latest live updates.
5:10pm - Winston Peters an 'egotistical narcissit' - Peter Dunne
Former leader of United Future Peter Dunne has issued a string of tweets labeling Winston Peters an 'egotistical narcissit' if he announces the next Government himself.
"It would be best for the successful leader of the lead party of the next coalition, and not the dog's tail, to get to announce the outcome," he said, over several tweets.
"That way, their credibility would be clear from the outset and they would look more than just a plaything."
"A better man than a egotistical narcissist would let the next PM announce they "were now able to form a Government with the support of..."
3:46pm - Jeanette Fitzsimons over it
Former co-leader of the Green Party Jeanette Fitzsimons has been helping the Greens with their Government formation talks.
"I've been down here for weeks," she told Newshub.
Is she sick of it?
3:19pm - Peters 'not aware' of any approach from Greens
Mr Peters says he's not aware of any approach from the Greens asking to meet with him.
Mr Peters refused to say whether he is open to talks with the Greens.
3:15pm - Talks with National wrap
NZ First and National have wrapped up the afternoon's talks.
Finance spokesperson Steven Joyce gave the thumbs up as he left.
The next meeting will be between NZ First and Labour at 4pm, followed by a meeting between NZ First and National at 6.30pm.
1:09pm - Greens won't meet with NZ First
Green Party co-leader James Shaw says there are no plans to meet with NZ First, even though staff have tried to set up a meeting.
When Mr Shaw was asked by Lloyd Burr whether he'd reached out to Winston Peters and asked for a meeting, Mr Shaw said, "We've had staff-level contact, but we knew all along that these meetings would be conducted in parallel."
Mr Shaw said it's normal for smaller parties not to meet up, even though they could end up around the same cabinet table.
"This is just what happens in normal negotiations, that there is a lead partner in the Government - obviously Labour - and it is their responsibility to form the Government."
Mr Shaw said things are different now compared to 12 years ago - which is when Labour worked with NZ First on a confidence and supply deal, with the Greens left out of Government.
"I think a lot's changed in the past 12 years, both in personnel and water under the bridge, so I've got a really good feeling about the way things are shaping up."
Mr Shaw made the remarks as he was entering a meeting with Labour.
Mr Shaw said the Greens' special general meeting needed to approve a deal could be done quickly.
1pm - National doesn't bring the biscuits - "just policy"
When asked whether Bill English would be taking biscuits into his meeting with NZ First this afternoon, Mr English said, "No. Just policy."
12pm - Winston Peters vs Lloyd Burr
Winston Peters says if Newshub politics reporter Lloyd Burr continues asking "stupid questions" then he will announce his decision on TV1.
Mr Burr had asked Mr Peters if he still lives in Whananaki. Mr Peters said he does.
11.49pm - Labour emerges from meeting
The Labour negotiating team has wrapped up its meeting with NZ First. It will meet with the Greens at 1pm, then again with NZ First later today.
Labour described this morning's meeting as "productive", which has probably been this week's most-used adjective.
While Labour meets with the Greens, NZ First will meet with National.
11.24am - Greens say Nats were considering fuel tax
Newhub's John-Michael Swannix has been looking into allegations National was considering implementing a fuel tax - one of the taxes National attacked Labour for allowing councils to implement.
Documents released to the Greens show the Government was considering the tax, which would be applied at the petrol pump, to pay for transport projects.
On the campaign trail, National focused heavily on the taxes Labour was planning.
Green MP Julie Anne Genter says it's hypocrisy. "The National Government [were] promising even more highways, secretly planning a regional fuel tax and basically lying to voters," she told Newshub.
National's been called out previously on its campaign strategy, which alleged an $11.7B fiscal hole in Labour's budget - a hole no economists were able to find.
11am - Meet new Labour MP - and new mum - Kiritapu Allen
As negotiations take place, let's meet one of Labour's new MPs.
Ms Allan has a new baby, who she said she wants to raise in a reo kāinga
- a Māori language home.
Ms Allan said Ms Ardern's leadership signals a new era in Labour's relationship with Māori.
Ms Allan was 19 years old, interning in Helen Clark's office during conflict over the foreshore and seabed.
"It was heartbreaking", she said. She told The Hui she was most aggrevied over legislating away the court process.
10:20am - Golriz Ghahraman: 'Parliament way more efficient than UN'
Green MP Golriz Ghahraman has arrived at Parliament for her first day, after the party gained a seat on the special votes.
Ms Ghahraman, who worked as a lawyer at the United Nations, said "Parliament so far is way more efficient than the UN."
She might find that's something to bond with Mr Peters over - he has previously described the UN as "top heavy, a law unto themselves, throwing down money like an eight-armed octopus."
When asked about the current negotiations, Ms Ghahraman said the Greens haven't been left out.
"Not at all. We have been really actively involved in negotiations, as far as I can tell."
She wouldn't comment on whether the Greens have had any talks with Mr Peters.
10:10am - ACT's David Seymour calls for merging of ministers
NZ First and ACT have one thing in common - they both want smaller Government.
During his campaign launch, Mr Peters called for two referenda on the same day; one asking whether Māori seats should be abolished and another asking whether Parliament should be reduced to 100 seats.
David Seymour put out a press release this morning saying 76 portfolios and 28 ministers could be reduced to 35 portfolios and 20 ministers in cabinet.
"We have a Minister for Building and Housing, a Minister for Building and Construction, and a Minister for Social Housing. What we don’t have is an adequate supply of housing, what we need is one person who’s responsible for fixing that," he said.
The attack may be a veilled attempt to keep Mr Peters' MPs out of portfolios, particularly as ministers outside cabinet.
On Twitter last night, senior NZ First MP Tracey Martin hurled some serious sass at Mr Seymour, saying "Gosh, he spends a lot of time thinking about Winston. We don't think about him at all. Sad, really."
9:57 - Todd McClay returns to negotiations
National's trade spokesperson Todd McClay wasn't part of negotiations on Sunday, but he did take part on Monday.
Mr McClay's father, Roger McClay, was one of Mr Peters' top advisors.
9:49am - First day on the job for Green MP Golriz Ghahraman
New Green MP Golriz Ghahraman has arrived for her first day of work.
Ms Ghahraman just missed out on a seat on the election night count, but the special votes saw the Greens gain a seat in Parliament.
She will be New Zealand's first refugee MP.
9:30am - Winston Peters' team
Newshub politics' Lloyd Burr says Winston Peters wandered to the meeting alone from his office in Bowen House, next to the Beehive. He probably called into Parliament's cafe, Copperfields, on the way, as he left very early.
Ron Mark, Jenny Marcroft, and Darroch Ball departed about 15 mins later. Ms Marcroft said she was not on the negotiating team. Mr Ball refused to answer questions, and Mr Mark had a massive grin on his face.
9:28am - But what about the biscuits?
We can finally say with great certainty two things Labour has brought to talks with NZ First today: gingernuts and chocolate wheatens.
9:19am - "There's certainly common ground"
On The AM Show this morning, Labour leader Jacinda Ardern said "there's certainly common ground" when it comes to NZ First and Labour policies, but she said she's not going to make any assumptions that policy similarity "will naturally mean
anything for us particularly."
8:50am - Winston Peters as PM a "ludicrous" idea
This morning on The AM Show, Labour leader Jacinda Ardern said the idea Mr Peters could end up Prime Minister is "ludicrous".
ACT's leader and sole MP David Seymour told Duncan Garner being Prime Minister "is the one big prize for Winston Peters."
Ms Ardern said the discussion has focused on policy, not roles.
More on that story - and watch the interview - here.