Wrexham AM Dr John Marek has resigned as chair of the Welsh assembly's house committee, it has been confirmed.
Dr Marek is in a long-running dispute with Lord Elis-Thomas
Dr Marek had denied reports he resigned as chair of the committee, which has a key role in how the assembly is run, following a meeting in September.
But spokesperson for the Assembly Parliamentary Service confirmed on Thursday that Dr Marek had stepped down.
Conservative AM William Graham will take over as chair.
It was reported that Dr Marek had resigned from the house committee on 28 September following a meeting to discuss the assembly's budget for 2007.
Other AMs present reported an angry exchange of views between Dr Marek and assembly presiding officer Dafydd Elis-Thomas, which was followed by Dr Marek announcing his intention to resign.
Dr Marek denied the reports but it has now been confirmed that he has stepped down.
The episode was the latest in a series of disagreements between Lord Elis-Thomas and Dr Marek, who is also deputy presiding officer.
First Minister Rhodri Morgan said: "It's been a very strange situation and it's not brought to end by this decision.
"Clearly we need a healthy relationship between the presiding officer and the deputy presiding officer and we don't have one at the moment."