Former Labour and Respect MP George Galloway is to stand as an Independent candidate in a bid to succeed Sir Gerald Kaufman as MP for Manchester Gorton.
Mr Galloway - who was expelled from Labour in 2003 after being found guilty of bringing the party into disrepute - branded Labour's shortlist of five ethnic minority contenders to be its candidate as an "insult" to the local community.
The 62-year-old claimed the shortlist had be engineered by National Executive Committee member Keith Vaz, who sits on the selection panel for the constituency.
"The 'All-Asian short-list' hand-picked by Keith Vaz is just not good enough for the people of Gorton, one of the most deprived constituencies in Britain," said Mr Galloway.
"The short-listing, which excluded many better candidates, is the latest in a long line of insults delivered by mainstream parties to local communities."
Announcing his candidacy on the Westmonster website, Mr Galloway said that ousting Labour from a stronghold which it has held since 1935 and won by a margin of 24,000 votes in 2015 would be "the mother of all by-election victories".
The by-election was triggered by the death of Sir Gerald Kaufman, the longest serving MP, in February.
Sir Gerald held Gorton in 2015 with 67% of the vote, ahead of the Greens on 9.8%, the Conservatives with 9.7% and Ukip with 8.2% of the vote.
The date of the by-election is yet to be fixed.
On Labour's shortlist for the by-election are North West MEP Afzal Khan and city councillors Yasmine Dar, Amina Lone, Luthfur Rahman and Nasrin Ali.
The Greens, who took second place in Gorton at the last general election, have selected entrepreneur Jess Mayo as their candidate.
The Liberal Democrats, who slumped to fifth place in 2015, will be represented by former Gorton councillor Jackie Pearcey.