Senior figures from the Conservatives and Liberal Democrats are continuing to hold discussions about forming the next government.
Who is doing the negotiating on either side?
The shadow foreign secretary and unofficial deputy Conservative leader heads up the Tory team. A Cabinet minister in the Major government, he was elected Tory leader after the party's 1997 defeat. He stepped down from the post after the party went down to another heavy loss in 2001. After four years on the backbenches, he return to David Cameron's shadow cabinet in 2005. Of those in Mr Cameron's inner circle, he is regarded as having the closest links with the right of the party and is keen to repatriate powers from Europe.
The shadow chancellor is among Mr Cameron's closest confidants, having run his successful leadership campaign in 2005. First elected to Parliament in 2001, he rose quickly through the ranks and was appointed to his current role at the end of 2005. He is credited with coming up with the Conservatives' key tax commitments and ran the election campaign. If the Tories enter government, he will become one of the youngest chancellors for many years.
Author of the party's election manifesto, he has been an important - albeit lesser profile - figure in Conservative ranks for many years. He worked for Margaret Thatcher in the 1980s and was shadow home secretary and shadow chancellor between 2001 and 2005. He has since taken a more back-seat role, focusing on policy formulation. He was thought to be in danger of losing his Dorset West seat at the election but won it with an increased majority. Once described as the "Gandalf" of Mr Cameron's inner circle - a cerebral figure who was behind some of the Tories' big ideas in recent years.
David Cameron's chief of staff worked for Chris Patten when he was Governor of Hong Kong. He has links with senior Liberal Democrats, having advised its former leader Lord Ashdown when he was the UN's senior diplomat in Bosnia and worked alongside Nick Clegg's wife, Miriam, when both worked for Mr Patten when he was an EU commissioner.
THE LIBERAL DEMOCRATS
Lib Dem leader Nick Clegg's chief of staff and right-hand man. Former media chief of pro-euro campaign group Britain in Europe, which brought together leading Labour and Lib Dem voices with business groups. First elected to Parliament in 2005, he rose to prominence when Mr Clegg became party leader in 2007. He was the author of the party's 2010 election manifesto.
A former economist and journalist, who made a fortune in the City before entering politics. Has stood twice for the Lib Dem leadership, losing to Menzies Campbell and then narrowly to Nick Clegg in 2007. Currently home affairs spokesman, he is regarded as being on the left of the party.
A former City banker, Mr Laws succeeded Lord Ashdown as MP for Yeovil in 2001. One of the editors of the free-market 'Orange Book' pamphlet in 2004, one of the big influences on Lib Dem thinking in recent years, he is seen as being on the right of the party. As schools spokesman, he has found common ground with the Conservatives in certain policy areas. He has been touted for a possible Cabinet job in the event of a Conservative-Lib Dem coalition.
The party's deputy chief whip, he is thought to be closely in touch with its grass roots and acting as a sounding board for its members over a possible deal. A former Baptist lay preacher, he was first elected to Parliament in 1997.