To their bewilderment, Senator Hanson-Young matter-of-factly announced that her party had just returned a leader that would see the party ''marching to a slow death''.

After the election, at which the Greens bled a third of their vote, recriminations within the party have been swift. There is clear disquiet in the party's senior ranks about Senator Milne's leadership, but for the first time, it is out in the open. It was revealed last week six of the party's 18 most senior staffers, including Senator Milne's chief-of-staff Ben Oquist, had left.

One Greens senator told Fairfax Media: ''I believe all this [leadership speculation] is because there are concerns about where [Senator Milne] takes us in the next three years. If we have the same result we had this election, we will be gone; we can't afford to do it again.''

But who is driving the destabilisation in this post-Bob Brown era of the Greens?

Senator Hanson-Young, an outspoken and ambitious party room member, is often mentioned by her colleagues as one of the key destabilising forces. Four separate sources claim that she made a bid for the party's leadership team at Monday's party meeting, a charge she denies.

The story goes that Senator Hanson-Young tried to gauge support for her to run for deputy leader, a position now held by the member for Melbourne, Adam Bandt, who would then be propelled into the leadership. (Senator Hanson-Young would not comment on Saturday, other than to say ''that's just not true'').

But others suspect the rumours are being put about to deflect attention from 41-year-old Mr Bandt, coming as they do on the back of reports that he had tried to gauge numbers for a challenge last Monday. Mr Bandt issued a statement saying he and his leader were ''a strong, united leadership team'', and that he had never sought the position of leader. But his office would not respond to questions about whether others had urged him to run for leader.

This sort of publicly fought internecine warfare is nothing new to Labor but it is a shock to many in the Greens, who have never experienced the sort of leadership challenges normal to most political parties. There is a sense within the party that even to publicly discuss a possible challenge is impolite. Behind the scenes, the Greens have been a consistently unified presence in Federal Parliament.

But in the aftermath of the Greens'

election performance, in which the party's lower house vote dropped from 11.76 per cent in 2010 to 8.6 per cent, some within the party's senior ranks are concerned about Senator Milne's leadership, particularly her attempts to put a positive spin on a poor result.

Mr Oquist, an experienced political operator who had spent years fighting for the Green side of politics, quit early last week citing ''fundamental differences of opinion in strategy''.

A former staffer, who spoke on the condition of anonymity, says Senator Milne is ''in denial'' about the election result. ''She said this week she wanted to move to a 'campaigning phase'. Well, here's a tip, love. We've just had a federal election. What the f--k have you been doing all year?''

Senator Milne told Fairfax she took ''some'' responsibility for the party's election result - and losing about a third of its vote - and vowed to listen to supporters who abandoned the party.

''Of course, as the leader of any political party you take some responsibility for the outcome of that election, and certainly I have to take a share of that responsibility in terms of the outcome for the election both good and bad,'' she said. This included returning at least 10 senators to Parliament after the election, with new Victorian senator Janet Rice elected. (WA senator Scott Ludlam's position is still in doubt.) But Senator Milne dismissed reports there had been a foiled attempt by party insiders to install Mr Bandt as leader, saying there was no threat to her leadership. ''It's wrong.''

NSW senator Lee Rhiannon leapt to Senator Milne's defence, saying: ''I figure if someone is going to mount a challenge, they're going to lobby for numbers. I wasn't lobbied. I just do not believe there was a challenge.''

While she acknowledged the Greens had ''a challenging election and a challenging election result'', Senator Rhiannon said the party room shared responsibility for the low vote. ''I think what we need to be looking at is how we project our message to voters.''

The party's campaign committee will review the election result and report to the Greens' national conference in November.