THE Labour leader at the centre of a plot to oust the mother of First Minister Nicola Sturgeon from her key council post has himself quit.

Just 48 hours after the authority's SNP administration announced it was resigning en mass, Peter McNamara has announced that he is stepping down with immediate effect as head of North Ayrshire Labour Group.

Mr McNamara said he was bringing forward a pre-arranged decision to step down due to the political crisis engulfing the authority.

READ MORE: Joan Sturgeon and SNP colleagues have stepped down as administration of North Ayrshire Council after by-election defeat

But opponents have said the move is indicative of power struggles within Labour and the resignation now makes it more likely party "young Turks" will attempt to form a new administration.

Mr McNamara was a due to stand down next May after 29 years as a councillor. He would have earned an additional five-figure sum had he become council leader until next May.

READ MORE: Joan Sturgeon and SNP colleagues have stepped down as administration of North Ayrshire Council after by-election defeat

Joe Cullinane, the youngest member of the Labour group and who only became a councillor in 2012, now heads the party and is likely to become North Ayrshire leader by the end of the month.

Mr McNamara said: "I have thought long and hard about whether to stand next year and have decided that now is the right time for me to seek pastures new.

"I was planning to step down as group leader in two weeks time but given the urgency of the current situation facing the council I have brought that forward. Later this afternoon the Labour group will hold its AGM and a new leader will be elected. That leader will allow the group to take a fresh approach as we face the challenges ahead."

READ MORE: Joan Sturgeon and SNP colleagues have stepped down as administration of North Ayrshire Council after by-election defeat

Earlier this week Ms Sturgeon's mother Joan announced she was standing down as provost of North Ayrshire as part of an SNP mass resignation.

It followed the failure of the First Minister’s father Robin to become the third member of his family to win elected office in Scotland, leading Labour to signal its intent to stage a takeover and seize control of the council.

The party's victory in Irvine last week left it with 12 councillors to the SNP's 11, with six independents holding the balance of power.

Mr McNamara, who represents Ardrossan and Arran, had told The Herald on Tuesday: "The SNP and independents combined outnumber us but there are ongoing discussions about this.”

READ MORE: Joan Sturgeon and SNP colleagues have stepped down as administration of North Ayrshire Council after by-election defeat

Labour said an AGM had been scheduled to take place on September 6 where a new leadership team would be elected by the group but given the current situation with the SNP administration resigning it had been brought forward to Friday afternoon.

But one SNP source said: "Yes Peter was going to stand down and yes he has been unwell. But if this was purely his decision he would've continued as leader of the council. When he became leader it was by a majority of one vote.

READ MORE: Joan Sturgeon and SNP colleagues have stepped down as administration of North Ayrshire Council after by-election defeat

"There are tensions there, Corbyn versus Smith and how the deal with now being the majority party. There's young Turks in there who probably don't recognise the challenges of administration in the way Peter does.

"I think it means there's more a likelihood they will attempt to form an administration."

Mr Cullinane said "Thanks are due to Peter McNamara for his long and dedicated service to the people of North Ayrshire.

"I know the council is facing many challenges but I am looking forward to working with my Labour colleagues on facing those challenges head on."

