By Cindi John
BBC News community affairs reporter
Labour's duty to ethnic minorities will be tested by its choice of candidate to fight a general election in the "least white constituency", a race group says.
All-women short-lists have boosted the number of Labour's female MPs
Operation Black Vote (OBV) says the case for "all-black" shortlists will be stronger if a white candidate wins the all-women contest to stand in West Ham.
OBV is urging the five black and Asian candidates in the multi-ethnic east London constituency to "unite".
It says one of two white candidates will win if the black vote is split.
Ethnic minorities make up 8% of the United Kingdom population but only 2% of MPs - 13 out of 659.
If ethnic minorities were represented in the House of Commons in proportion to their numbers in the population, there would be 42 ethnic minority MPs.
The Labour party leadership has admitted it needs to address the issue surrounding the number of ethnic minority MPs, but the party was unavailable for further comment ahead of Saturday's contest.
Party chairman Ian McCartney recently announced a consultation exercise on all-black shortlists.
A spokesman for OBV, which describes itself as an initiative to focus exclusively on the black democratic deficit in the UK, said Saturday's contest was so close that second preference votes would be "critical".
Ashok Vishwanathan said: "We have asked some of the candidates who aren't the front-runners to ask their supporters to give their second preference to one of the two front-runners," Mr Vishwanathan said.
OBV has argued the failure of all-women shortlists so far to deliver an ethnic minority prospective parliamentary candidate for the next election means Labour should introduce ethnic minority-only shortlists.
The Commission for Racial Equality is also calling for ethnic minority-only shortlists in certain circumstances such as those in West Ham.
Figures from the 2001 Census showed the constituency of West Ham, where veteran MP Tony Banks is standing down, has an ethnic minority population of 55%.
"It would be terribly disappointing if in the least white constituency in the whole of Europe, we didn't have a minority candidate," CRE chairman Trevor Phillips said last month.
Tories 'on course'
Twelve of the 13 black or Asian MPs at Westminster represent Labour. However, critics such as OBV say the Conservatives, who currently have no minority MPs, are on course to get more new ethnic MPs elected to the next Parliament than Labour.
Diane Abbott (Lab)
Paul Boateng (Lab)
Parmjit Dhanda (Lab)
Mark Hendrick (Lab)
Piara Khabra (Lab)
Oona King (Lab)
Ashok Kumar (Lab)
Khalid Mahmood (Lab)
David Lammy (Lab)
Mohammad Sarwar (Lab)
Marsha Singh (Lab)
Parmjit Singh Gill (Lib Dem)
Keith Vaz (Lab)
The Conservatives have selected a black man - Adam Afriyie - for Windsor and an Asian - Shailesh Vara - for North West Cambridgeshire. Both seats are currently held by the Tories.
They also have two ethnic minority candidates in seats with only a slim Labour majority.
To date, only two candidates of ethnic minority origin - Sadiq Khan and Shahid Malik - have been selected by Labour to stand in seats currently held by the party.
An Asian woman, Yasmin Quereshi, has been selected to stand in Brent East in north-west London after an open selection contest.
Brent East had been the long-time seat of Ken Livingstone.
The Lib Dems won a by-election there called in the wake of the death of Paul Daisley after a long battle with cancer.