It was Friday night, just hours after his other deputy leader, Scott Ludlam, had resigned in a shock press conference, having found out he was a citizen of New Zealand.

When Waters broke the news that she too had discovered she was a dual citizen and therefore ineligible to sit in Parliament, initially, the Greens leader didn't believe her.

"For a split second, I thought it was a joke, but from the tone of her voice, it was pretty clear she wasn't joking," Di Natale recalls.

The loss of two high profile Greens senators in the space of five days has been described by party insiders as "heartbreaking", "super bad luck" and "nuts". They will regain the numbers in the Senate, with the vacancies expected to be filled by other Greens candidates. But the party is reeling after losing both deputy leaders and two of its most high-profile parliamentarians.

Dr Stewart Jackson, a Sydney University lecturer in green politics and former Greens national convenor, says Ludlam and Waters were considered potential future leaders.

"I think they're both really serious losses, particularly given they were both really bright stars."

It had already been a monthus horribilis for the Greens. While they dithered about their final position on the Gonski 2.0 school funding bill, the government went off and did a deal with other crossbenchers. In the wake of this, the party room wrote a letter complaining NSW Greens senator Lee Rhiannon had undermined the Gonski deal. The letter was leaked, exposing fault lines between the national and NSW arms of the party and leading to headlines blasting about a "civil war".

So where to now?

Di Natale has ordered a review of party processes, to ensure no one else is caught out by the dual citizenship rule again. The review, which so far does not have a timeframe, will also look at accountability and transparency issues within the party.

It hasn't helped that in recent days there have been questions about Di Natale's own status, although he tweeted proof he was not an Italian citizen on Friday afternoon. There have also been queries about the eligibility of Tasmanian senator Nick McKim, as a former British citizen, and Waters' replacement Andrew Bartlett, because he was working for a university at the time of his nomination.

The Greens leader, however, insists no more resignations will be required.

"We're very confident there are no remaining issues with regards to our MPs or future MPs," he says.

In the short-term, the Greens have some waiting to do. The process to replace Ludlam and Waters could take until October. The Senate needs to refer the matter to the Court of Disputed Returns and the Senate can't do that until it sits again in August. On Thursday, party whip Rachel Siewert and party room chair Adam Bandt were made temporary co-deputy leaders. But a final decision and rearrangement of portfolios will have to wait until the new senators arrive in Canberra.

This paves the way for a shift in the power dynamics of the party. As one Greens member noted, Bandt is now the only realistic alternative to Di Natale as leader - although there is no serious speculation about a leadership change anytime soon.Bandt has been deputy leader before, under Christine Milne. But he lost the spot when Milne resigned and there was an almost instantaneous ballot to elect a new leadership team. Some within the party feel this timing disadvantaged Bandt's chances.

It will be up to the party room to decide whether they elect two deputy leaders, as they did last time with Ludlam and Waters, or stick with one.

When asked if there needs to be diversity in the Greens leadership, Di Natale notes it is a "decision for the party room". But adds, "it would be my strong view that given we've got such a proud record of having gender representation that that would be reflected in the leadership of the parliamentary team".

If there is only one deputy leader, this could count against Bandt, who is Victorian, like Di Natale, and open the door to someone like Siewert. The party's community affairs spokesperson is regarded as a hard worker, even if she does not enjoy the same public profile as other Greens. Sarah Hanson-Young has put her hand up before, but did not get the support of her colleagues. Former Tasmanian Greens leader McKim, who has 15 years experience in state parliament has also been floated.

All this upheaval comes as the Greens look towards a critical federal election, expected in 2018 or 2019. At the next national poll, the Greens will have six of their nine senators up for re-election, as well as Bandt recontesting his lower house seat of Melbourne. Party insiders are predicting it will be tough to hold onto to Hanson-Young's South Australian seat, in part due to the Nick Xenophon factor. In Queensland, with One Nation chipping away at protest voters, Waters' replacement (likely to be former Democrat leader, Bartlett ) is tipped to struggle.

While the resignations of Ludlam and Waters see the Greens lose two of their best performers, party watchers don't see it as a mortal blow. Associate Professor Anika Gauja researches political party organisation at Sydney University and notes that the Greens' 10-member federal party room is "more than the sum of its parts". She adds that as a minor party, many voters would struggle to name the Greens leader, let alone the other members of the team.

"I don't think the loss of particular senators is going to be the end of things for them."

On the bright side, some within the party think the dual citizenship catastrophe may mean that the infighting with Rhiannon and her supporters in the NSW Greens subsides - at least for now. While Di Natale will not be drawn on his NSW colleague, he notes, "in moments like this it often brings people together. I'm very confident that we'll come together as a party room stronger than before."

There is also great optimism around Ludlam's likely replacement, the 22 year-old disability activist, Jordon Steele-John, who uses a wheelchair.

"I'm really looking forward to getting the carpenters into the Senate and watching them put in some ramps," Di Natale says. "While Scott's irreplaceable, the likely election of Jordan to the Senate is going to be transformational in terms of the voice he gives people living with disabilities and young people."

The most recent Essential Report, released on Tuesday (after the Ludlam news but before Waters' resignation) suggests the party's standing with the public has not taken a significant hit so far. The Greens polled 10 per cent, in keeping with their 10.2 per cent lower house primary vote result in the 2016 election. The Essential Report result was down a point from the previous week (before Ludlam's news), but was up from 9 per cent at the height of the Gonski debate month ago.

But predictions about the demise of the Greens are certainly not new. Former leader Bob Brown quitting Tasmanian state parliament in the 1990s for Canberra was supposed to bring about the end of the party. As was his retirement from federal politics in 2012 and then Milne's exit in 2015.

Brown himself is unfazed about the current state of play.

"I can't emphasise too much how much people have counted the Greens off all the way down the line ... once again, they're crying foul but the Greens will go on to bigger and better things."