Foreign Secretary David Miliband is the clear favourite to succeed Gordon Brown as leader of Britain's Labour party and potential prime minister, although the contest must wait until a new government is formed.
Miliband's main competitor would likely be Schools Secretary Ed Balls but any number of candidates could still declare -- including Miliband's younger brother, Ed -- as different party factions vye for power.
Brown announced Monday he was stepping aside after his party came second in Thursday's elections, saying Labour would choose a new leader by the party's annual conference in September.
There is a chance the winner could also become prime minister because both Labour and the Conservatives, who came first, are still locked in talks with the third-placed Liberal Democrats to form a government.
Although the Labour leadership race will not start until a new government is formed, the bookmakers' have already picked Miliband as odds-on favourite.
The brainy 44-year-old worked closely with former Prime Minister Tony Blair, both as head of policy before Labour was elected to government and for four years after they took office.
He was elected to parliament in 2001 and rose swiftly, becoming environment secretary in 2006 and then foreign secretary in June 2007.
Despite some hiccups -- he sparked outrage during a trip to India in January 2009 by linking the unresolved Kashmir dispute to the Mumbai attacks -- he has won respect and was mooted as a candidate for EU foreign affairs chief.
Miliband's reputation took a knock in 2008 when he tentatively challenge Brown's leadership but then backed off, and was later photographed in a ridiculous pose holding a banana, for which he was widely mocked.
Two years on, Miliband has returned as a clear leadership contender, although he must boost his grassroots support.
He appeared to include himself among those running Tuesday, telling reporters: "I'm not going to be saying anything more and none of the candidates are going to be saying anything more either."
Miliband is thought to have the support of Alan Johnson, the home secretary and former postman who was himself once touted as a future leader.