The leader of Wigan Council is to step down after 27 years in the post.
Lord Peter Smith - the longest serving council leader in Greater Manchester - said it was "now time to pass the baton" to a new leader.
He will continue as a councillor and chairman of the Greater Manchester group responsible for the region's devolved healthcare.
Greater Manchester Mayor Andy Burnham described him as "a great friend and mentor" and "outstanding leader".
The new leader will be chosen by the Labour group on 14 May.