Labour supporters are casting their votes in a ballot which could decide who becomes a Member of the European Parliament next year.
Party members have been asked to vote to determine which of four candidates ranks highest in the ballot for the Euro elections in May.
Leicester's deputy mayor Rory Palmer is one of the candidates and, should he get the most votes from East Midlands Labour members, he will be second on the ballot paper behind sitting Labour MEP Glenis Willmott.
The Euro elections use a proportional representation system so the higher ranked the candidate, the better the chance of them winning a seat in Brussels should voters back Labour in May.
Leicester MPs Keith Vaz, Liz Kendall and Jon Ashworth have all pledged their support to Coun Palmer's campaign, as has his boss, city mayor Sir Peter Soulsby.
The internal Labour ballot opened on Friday and runs until July 31. The result will be announced in September.
Coun Palmer's Labour rivals are Nicki Brooks, Khalid Hadadi and Linda Woodings.
Ms Brooks is a Gedling borough councillor and has been an active member of the Labour Party for more than 20 years.
Mr Hadadi is a Brussels-based European affairs manager for Channel 4. He was formerly an employment guidance worker for Leicester City Council and carried out voluntary work focussing on urban regeneration in the city.
Ms Woodings is political officer for the East Midlands branch of the Communications Workers Union.
