Former Sheffield MP, Richard Caborn, has said the Labour Party's selection procedures for the city region mayor shortlist were 'unfair and undemocratic'.
Last month, Mr Caborn said he was 'surprised an disappointed' not to be selected as one of the candidates who will be voted on by party members in South Yorkshire later this year.
And today, he revealed that he had written to the general secretary of the Labour Party - and had spoken to its deputy leader, Tom Watson - outlining his concerns and asking for a series of recommendations to be acted upon.
In his letter, Mr Caborn said he 'did not understand' the selection panel’s reasons for withholding him from the shortlist - especially when the longlist had only three names.
He said: "I strongly disagreed with the panel’s feedback that I ‘did not demonstrate enough campaign experience’, when I have been campaigning for the party for almost sixty years.
"To say I ‘did not show commitment to mobilising members, raising funds and raising media interest’ is perplexing when many party members across South Yorkshire would agree that these are indeed my strengths.
"I was also surprised to discover that ‘I did not demonstrate enough understanding of South Yorkshire’, when I was not only born and raised in the region, but I was the only candidate originally from South Yorkshire.
"Furthermore, I informed them that I was penalised for my strong economic focus when the powers associated with the Mayoral role are predominantly economic.
"I also explained that I was criticised for seeking to reverse the under-representation of women in highly paid and highly skilled jobs, when this should be welcomed as a key driver for equalities and social justice; which is what our party stands for."
Mr Caborn said he believed the shortlisting process was 'unfair and undemocratic' - not just to candidates, but to the membership and the wider public.
And he requested that a review take place into the procedures to ensure that the party learns from its 'mistakes'.
Mr Caborn - who served as MP for the Sheffield Central constituency between 1983 and 2010 - also makes a series of recommendations for future selections.
These include a recommendation that the majority of any selection panel members should be local residents from the area where the election is actually taking place and that a minimum of three candidates should be on the shortlist for members to vote on.
He also thinks a 'basic appeals process' should be implemented and a job description should be made public, so that there is no dispute as to what the successful candidate’s role will entail.
"I trust the party will now review the South Yorkshire mayoral selection process to learn valuable lessons, take on board my recommendations, and ensure that future selection processes are more democratic, transparent and fairer for everyone involved,” he added.
Labour Party members will now choose between Barnsley MP Dan Jarvis and Sheffield city councillor Ben Curran, before the wider electorate get their chance to vote for mayor in May.