Former Birmingham cabinet member John Tyrrell, who quit the Labour Party on Sunday, is to stand for the far-left Socialist Labour Party in next month's city council elections.
Mr Tyrrell will be a candidate in Handsworth Wood ward, in a move that could split the Labour vote and potentially deliver the seat to the Conservatives.
He resigned from Labour's ranks after more than 40 years' membership, blaming his decision on "right-wing policies" and heavy-handed control by the party's West Midlands regional office.
Although Labour had a majority of just over 1,000 in Handsworth Wood in the 2006 council elections, Mr Tyrrell is a well-known figure who served as a councillor for nine years and could attract support.
His resignation followed a bitter three-year tussle with the regional party, which approved the deselection of Mr Tyrrell and fellow left-wingers Phil Murphy and Gurdev Manku in 2004.
Announcing his decision to stand as a Socialist Labour candidate, Mr Tyrrell said he would fight on a platform to support people from all sections of the community who found difficulty in accessing council services.
He said: "I think people made it abundantly clear that an imposed candidate will not get support in a campaign. The view is 'let the Birmingham Labour Party fight the campaign' if they wish to decide who represents the ward."
Mr Tyrrell added: "I am considering standing, as an independent or as a member of another political party, and I have been approached by the Socialist Labour Party."
He said it was a "possibility" that, by standing, the Labour vote could be split. He hit out at the regional office, which failed to respond to a series of angry letters and emails. Mr Tyrrell said: "Members of this ward are extremely angry at the discourteous way they are treated. Members are beneath contempt in the view of the regional office.
"Party members don't have a say, aren't allowed to meet or to put resolutions forward. Many people I speak to, long standing party members, have simply had enough."
West Midlands Labour Party was unavailable for comment.