The identity of Britain's next prime minister could take days to emerge, with Gordon Brown and Conservative leader David Cameron in frantic battles for the keys to 10 Downing Street after a cliffhanger election.
With neither the Tories nor Labour winning the key 326 seats needed for a majority government, a hung parliament was declared as vote counting began wrapping up on Friday.
While the Tories were on track to win the most seats in the tightest election race in decades, Mr Brown refused to accept his Labour government had been defeated.
Under Whitehall rules, Mr Brown has the first chance to form government by doing deals to sure up support from smaller parties such as the Liberal Democrats.
If he fails, he is likely to resign and leave the Queen to invite Mr Cameron to form a government.
Both leaders returned from their constituencies to London early Friday to begin what is expected to be days of talks with party powerbrokers, minor parties and civil servants about who should rule the country.
Brown said to negotiate
Mr Brown is expected to speak with the Lib Dems, Welsh and Scottish nationalists, the SDLP and Britain's first Green MP, Caroline Lucas, in the hope of sealing a pact allowing Labour to remain in office for a historic fourth term.
Mr Cameron has previously indicated he would be prepared to lead a minority government, with possible support coming from Northern Ireland MPs and other minor parties.
He told supporters in his constituency of Witney the Tories were on track to win the most seats in 80 years and that Labour had lost the mandate to rule.
"What's clear from these results is that the country, our country, wants change," Mr Cameron said.
"That change is going to require new leadership and we will stand ready to do all we can to help bring that leadership."
Brown still holds power
But Mr Brown signalled he was determined to cling on to power, saying that as Labour leader he had a "duty to the country".
"My duty in all of this is that there be a stable, strong and principled government and to play my part in making that possible," he said.
"I think it is too early to say what the verdict of the people is but it is pretty clear that what the people will want at the end of this election is a government that is strong, stable and principled."
Labour powerbroker Lord Peter Mandelson appeared to suggest in one interview that Mr Brown might have to step down if it was the price Labour had to pay to secure the backing of other parties to allow it to remain in government.
"Frankly, there are quite a number of permutations," he told the BBC when asked if it would be inconceivable to have a Labour minority or coalition government without Mr Brown as prime minister.
"I don't want to start getting into hypotheses about what may or may not happen. I think it is premature until all the results are in.
"I am not ruling out or ruling in anything."
Lib Dems 'dissapointing'
The Lib Dems and leader Nick Clegg had enjoyed a surge in popular support during the four-week election campaign and even overtook Labour in some opinion polls.
Mr Clegg described the Lib Dems' performance as "disappointing" amid fears the party would finish with fewer MPs than the 63 it had elected in 2005.
However he was coy about doing deals with either Labour or the Tories.
"People have voted but no one appears to have won emphatically," he said.
"I really think it would be best for everyone to take a bit of time and see what the final result is and take it from there."
Voter turnout for the election was extremely high, with some people turned away from polling stations as they closed their doors at 10pm local time on Thursday (EDS: 0700 AEST Friday).
While the Greens celebrated the election of their first MP, Labour's former home secretary Jacqui Smith lost her seat, along with several other junior ministers.
Millionaire Zac Goldsmith, brother of socialite Jemima Goldsmith, won Richmond Park for the Tories while the far right British National Party leader Nick Griffin failed to win the London seat of Barking.
