The embattled Greens MP Jeremy Buckingham will face another internal challenge to push him out of the party this weekend, as in-fighting continues to grip the New South Wales branch.

Buckingham has faced persistent calls to resign since a party aide, Ella Buckland, made allegations in 2011. Greens MP Jenny Leong made accusations in NSW parliament that Buckingham committed an “act of sexual violence” against Buckland, though an independent investigation was unable to substantiate Buckland’s claims and Buckingham strenuously denies them.

A motion will be moved at the Greens NSW state delegates council this weekend, likely on Saturday, to remove Buckingham from the party. The Greens NSW standing campaign committee will move the motion of no-confidence, which has been seen by Guardian Australia.

“The Greens NSW has lost confidence in Jeremy Buckingham MP as a representative and spokesperson for the party and, therefore, determines that he should no longer be a Greens NSW candidate for the 2019 NSW state election,” the motion reads.

“[State delegates council] therefore requests that Jeremy Buckingham MP steps aside and vacates his position on the ticket.”

The motion also calls for a significant overhaul of Greens structures and complaints handling, guided by a “formal and independent review” that would focus on its capacity to deal with harassment and bullying. The review would begin on 1 January 2019 with a budget of $20,000.

Buckingham has claimed the moves against him are factionally motivated, a charge hotly disputed by his internal opponents. In an email sent to local Greens members late last month and seen by Guardian Australia, Buckingham said the motion of no-confidence was a “factional attempt to overturn a democratic grassroots preselection”. Buckingham also shared the findings of the confidential report into the allegations.

“Members will be aware that this is the third state delegates council (SDC) in a row where this type of proposal has been put since the preselection was ratified in May,” he said. “It follows a complaint lodged at the beginning of 2018 on behalf of Lee Rhiannon and Geoff Ash that sought to have me expelled from the Greens prior to the preselection, and the attempt to stop Cate Faehrmann running in the preselection that was overturned by the supreme court.

“Certain MPs and factional operatives have been running a smear campaign against me, have weaponised a sexual harassment claim and have used the media and parliamentary privilege to manufacture a sense of crisis to justify overturning the preselection result.”

Buckingham has been under pressure since Leong used a speech to parliament to urge him to stand down. She said the push to remove him was not motivated by factional manoeuvring but because of his treatment of women.

“Jeremy, you have had countless opportunities to take responsibility for this, to apologise to those impacted and to seek to address them,” she told parliament. “Instead, you have followed with further aggressive tactics. I know you feel like you are the victim of internal party attacks, but you must acknowledge your role in this and stand aside before more damage is done.”

He has previously claimed the attacks against him are driven by the Left Renewal faction, which internal sources say no longer exists in any serious form.

One of those calling for Buckingham to resign is Mehreen Faruqi, the federal Greens senator, who is not aligned with Left Renewal. Faruqi was recently locked in a preselection battle with Rhiannon, who the Left Renewal faction had backed.