The New South Wales Greens is headed for a spectacular split after the party called for Jeremy Buckingham to stand aside over an unproven sexual misconduct allegation.

His allies Cate Faehrmann and Justin Field sensationally threatened to quit the party on Wednesday unless those in the left faction were expelled.

In an email to state party members, seen by The New Daily, the two MLCs also called for a formal recount of preselection votes if Mr Buckingham withdraws from the upper house ticket.

It comes after the NSW Greens passed a motion by consensus on Saturday calling for Mr Buckingham to stand aside.

Mr Buckingham has repeatedly denied the allegation.

Moderates in the party say an allegation from former staffer Ella Buckland – which dates back to 2011 and was formally raised with the party in April this year – has been weaponised by the left faction.

An independent investigation by Workdynamic Australia found there was insufficient evidence “that a reasonable person could conclude, on the balance of probabilities” that sexual harassment occurred.

They recommended taking no action against Mr Buckingham.

NSW Greens MLC Cate Faehrmann is pictured. Photo: AAP

The investigators did not find the allegation was false, vexatious or made for political reasons, the Greens said in September.

Mr Buckingham is on the third spot on the upper house ticket, which is considered unwinnable.

He earned the second-most votes, behind his factional enemy David Shoebridge, but was relegated to the third position because party rules require at least one of the top two spots go to a woman.

It means Abigail Boyd was parachuted to the second spot.

Moderate Dawn Walker, who was preselected to the fourth spot, contacted the Greens’ head office on Tuesday to formally request a recount.

“In the event that Jeremy Buckingham is not on the NSW Greens Legislative Council ticket for the 2019 NSW state election, the preselection ballot that determined the ticket will have serious democratic flaws and the make-up of the ticket will not reflect the democratic intention of the members of the NSW Greens,” she said in an email seen by The New Daily.

Ms Walker would likely overtake Ms Boyd using Mr Buckingham’s preferences in the case of a recount.

She said a recount was vital to ensure his supporters were not disenfranchised.

In the email to members on Wednesday, Ms Faehrmann and Mr Field warned of an “irrevocable split” in the party due to instability they blamed on the left faction.

“The NSW Greens have been undermined by a deliberate and systematic effort by a small group of members motivated by extreme left ideology,” the email said.

“As a result, as Greens MPs who have dedicated decades to supporting, building and representing this party, we are giving serious consideration to whether we can continue as members of the NSW Greens.”

They have demanded the party commit to a recount and expel members who remain part of the left faction’s ‘left renewal’ and ‘solidarity’ groups by next Monday.

The email included a link to an open letter, which has been signed by dozens of party members including Ms Walker.

Ms Walker has formally requested a recount of preselection votes. Photo: AAP

The party rift was re-opened last month when Newtown MP Jenny Leong used parliamentary privilege to air the allegation and call for Mr Buckingham’s resignation.

On Saturday, the NSW Greens State Delegates Council passed a motion by consensus requesting Mr Buckingham vacate his position on the ticket.

Consensus requires 75 per cent support, while two groups registered their dissent.

The motion thanked and acknowledged Mr Buckingham’s “extensive and outstanding” work against coal and coal seam gas.

But it said the Greens would be unable to continue to campaign effectively if he remained.

Mr Buckingham slammed the party as “corrupt and rotten” in response.

He said he was assessing his legal options.