LONDON - Seven party leaders are headed into Britain's most unpredictable election in decades on Thursday, which has brought several smaller parties to the fore because of a fragmentation of the vote.

- David Cameron, 48, Conservative Party

 Accused of fighting a lacklustre campaign, Prime Minister David Cameron has turned up the passion as polls have indicated no late swing in his favour. His privileged background makes him the "posh" candidate, but he has told voters to look at his economic achievements instead of his background.

The son of a stockbroker, Cameron was educated at exclusive Eton College and Oxford University, where he was admitted to the Bullingdon Club - a hard-drinking, socially exclusive student group.

- Ed Miliband, 45, Labour Party

Written off as a weird Westminster insider who became Labour Party leader only by knifing his brother, Ed Miliband is now seen as having more than a sporting chance of being Britain's next prime minister.

Despite his awkward demeanour and frequent setbacks, Miliband has retained an unerring self-confidence, which a growing number of people believe could propel him to the country's top job. The son of a prominent Marxist academic father and a campaigning activist mother, Miliband grew up in a highly politicised household frequented by left-wing intellectuals from around the world.

- Nick Clegg, 48, Liberal Democrats

The deputy prime minister's experience in government has been damaging and polls suggest that he and his party are now so unpopular that he could lose his seat, ending his frontline political career. Many voters blame the centrist Liberal Democrats for propping up Cameron's Conservative-led administration as it introduced tough austerity measures to cut the deficit.

- Nigel Farage, 51, UK Independence Party

Farage has turned the UK Independence Party (UKIP) into a national force but is battling for his political future, with commentators saying that his populist campaign has run out of steam. Anti-Brussels and anti-political correctness, Farage, who once compared ex-European Council president Herman Van Rompuy to a "damp rag", led UKIP to top the polls in European Parliament elections in 2014.

- Nicola Sturgeon, 44, Scottish National Party

The steely and polished Scottish independence leader has emerged as an unlikely star of Britain's unpredictable election race and could decide who is prime minister after Thursday's election.

Once little known south of the border, Sturgeon has become one of the most talked-about figures in the campaign thanks to her performance in election debates - even though she is not running for a seat in Westminster herself.

- Leanne Wood, 43, Plaid Cymru

They may only win a handful of seats at next month's general election, but the Welsh nationalists could find themselves catapulted from relative obscurity to a position of influence across Britain.

- Natalie Bennett, 49, Green Party

The leader of the Green party has campaigned against austerity and looks set to pick up votes from the backlash against mainstream politics.

But she will struggle to win a seat and her party may end up with just one parliamentary victory.