Sefton Council Leader Cllr Ian Maher has resigned from his roles as council leader and leader of the Sefton Labour Group.
It is believed he will continue as a backbench councillor.
A process will now begin to seek his replacement.
No reasons for his departure have yet been given.
Cllr Maher has overseen a number of significant regeneration projects in Sefton since he was elected as leader in 2015. He took over from Peter Dowd, who became the MP for Bootle, a position he still holds.
Cllr was part of the successful bid for £37.5 million in Town Deal funding for Southport from the Government.
The funds have already supported the transformation of Southport Market into a vibrant new food, drink and events venue.
Further funding is also going towards the creation of the £73 million new Marine Lake Events Centre, the Southport Enterprise Arcade and Les Transformations de Southport, a series of public realm improvements in the town centre.
He also led the £32.5 million purchase of the Strand shopping centre in Bootle and the subsequent £20 million Levelling up bid from the government to continue the transformation of Bootle town centre, an ongoing process.
A Sefton Council spokesperson said:
“We can confirm that Cllr Maher has decided to step down from his role as Labour Group and Council leader.
“Cllr Maher has asked the Labour Group Executive to start the process for electing his successor as soon as possible.
“This process does not affect the day-to-day operations of the Council and once it has been completed, appropriate arrangements will be made to appoint the new Leader of Sefton Council in line with the Council’s constitutional requirements.”
Cllr Ian Maher has represented his constituents in Netherton and Orrell Ward as a Labour councillor since he was first elected on 6th may 1996.
He has been Sefton’s representative on the Liverpool City Region Combined Authority.
In 2002 he was re-elected for a new four-year term, surging to victory by securing 73% of the vote.