Councillor Pete Lowe is running for Mayor, as the "anti-austerity candidate", vowing to demand a backdated fair funding settlement for councils to reverse the impact of Tory cuts.
But he has come in for criticism from Birmingham Council's Labour chief whip Brett O'Reilly, who accused Mr Lowe of failing to pay the living wage to local authority workers when he ran Dudley Council.
In a now deleted tweet to Mr Lowe, Mr O'Reilly said: "Will he explain why as a former council leader he kept low paid workers in poverty by refusing to pay the real living wage?"
In response, Mr Lowe, a trade union officer with Managers in Partnership with the NHS, backed his record at the head of the council.
"When I left as leader last September I was proudly applauding the fact that Dudley was becoming not just a living wage employer, but a real living wage employer as outlined by the TUC," he said.
"I'm also proud of the fact that in my whole political life I have never had any dispute with any workers in any of those areas that I have been involved in.
"I have had a collaborative approach where we resolve issues by sitting down and engaging to find a solution.
"Certainly my approach to being Mayor will be to take people along and to combat those areas that divide us."
Mr Lowe is the third person to come forward for Labour, following former Stourbridge MP Lynda Waltho and Birmingham MP Liam Byrne.
Party members are set to elect a candidate in early autumn.
The region's election for the post currently held by Conservative Andy Street takes place next May.