Labour will announce later its candidate for Greater Manchester's first mayoral election in May.
Shadow Home Secretary Andy Burnham, Bury South MP Ivan Lewis and interim mayor Tony Lloyd are on the shortlist.
Voting by local party members who registered at least six months prior to a freeze date closed on Friday.
The deal for the elected mayor, which will include control of transport, social care, housing and police budgets, was announced in 2014.
Agreed by council leaders with the then chancellor George Osborne, it will give Greater Manchester control of about £2bn of government funding previously administered from London.
Labour will be the first party to announce a candidate for the election.
It will also confirm its candidate for the contest in Birmingham later on Tuesday, before revealing the Liverpool City Region candidate on Wednesday.
Who are the Labour Manchester candidates?
- Andy Burnham: The Leigh MP is the most recognisable candidate, having served in the Tony Blair and Gordon Brown governments. Born in Liverpool, the Everton supporter won praise for his work on the campaign for justice after the 1989 Hillsborough disaster.
- Ivan Lewis: Economic Secretary to the Treasury in the Blair era, he worked for voluntary organisations before becoming the MP for Bury South in 1997.
- Tony Lloyd: The long-serving politician was elected to parliament in 1983 for his local constituency of Stretford, but stood down as an MP in 2012 when he successfully contested the police and crime commissioner election. In 2015, he was appointed interim mayor of Greater Manchester.