Rajbir Singh sent shockwaves through Sandwell Council this week when he resigned after six months in the job, claiming he was unable to balance the role with family and business commitments.
Sandwell Council has now confirmed the 41-year-old has also stepped down as a councillor in Bristnall, where he was first elected in 2018.
The unusual move to quit partway through a term of office is likely to see the seat remain vacant until next May's local elections.
Labour councillors are also understood to be gearing up for a possible leadership election in the coming weeks, which is said to be an option under consideration by national party bosses.
Councillor Maria Crompton has taken over as interim leader for a second time, and has pledged "business as usual" and "stability" at the authority, which has had five leaders and three chief executives in the last three years.
She is yet to confirm whether she would stand in any leadership election.
Potential candidates are believed to include Councillor Kerrie Carmichael, who lost out to Mr Singh in May's election, and former cabinet member Councillor Simon Hackett.
Current environment chief Councillor Ahmad Bostan, a supporter of disgraced former deputy leader Mahboob Hussain, has also been mentioned as a possible candidate.
The council is also on the lookout for a new chief executive, although interviews for the role that were scheduled for next week are understood to have been cancelled without explanation.
Meanwhile the 24 Labour candidates for next year's council elections are expected to be announced in the coming days.