Former Plaid Cymru AM Neil McEvoy says he has withdrawn an application to re-join the party after he was expelled.
He said he had made the decision due to claims of an absence of "natural justice" and "due process."
In a letter to the party, the South Wales Central AM alleges two members of the panel that was to decide his fate had "expressed prejudiced views" about him.
Mr McEvoy also claims he had concerns over the timing and legal representations.
In March 2018 he was expelled from Plaid Cymru for 18 months for breaching the party's standing orders. It was later reduced to six months on appeal - but Mr McEvoy had to reapply to join the party.
In a statement Plaid Cymru said: