David Cameron, leader of Britain's opposition Conservative Party, leaves a polling station with his wife, Samantha, on Thursday in Whitney.Kirsty Wigglesworth/The Associated Press
The social contract between Britain's dominant political parties and the public that has underpinned three decades of strong governments came crashing down Thursday night in a bitter, chaotic election that seemed less a change of parties than a rejection of the institutions and methods of traditional politics.
Exit polls showed the opposition Conservative Party winning the most seats, though likely short of a majority, with Prime Minister Gordon Brown's Labour Party still holding enough seats that he could form a viable, if highly controversial, government with the third-place Liberal Democrats - a possibility that his ministers insisted early into the morning was still open.
With 615 of the 650 seats counted, the Conservatives had secured 290 seats, Labour 247, the Liberal Democrats 51 and smaller parties 27 seats. At least 326 of the House of Commons' 650 seats are needed to form a government.
Conservative leader David Cameron said the ruling Labour party had "lost its mandate to govern", and Prime Minister Gordon Brown was asked by a reporter whether he would resign as he returned from his constituency to his residence at No. 10, Downing Street.
He did not reply.
Under the constitution, Brown has the right to try and form a government first, potentially opening the door to a period of political horse-trading.
The precise shape of Britain's next government, and the arrangements that will allow it to maintain a hold once Parliament sits on May 16, will probably not be known until well into Friday.
But the results have been a backlash against established politics in a country devastated by bank failures and mounting public debt and deeply disillusioned by an expense-account scandal that shamed Labour and the Tories alike. This led to a fractious election, beginning with dramatic debates that changed a two-party system into a three-way race and ending Thursday night with physical violence at some polling stations as angry voters protested the rigid closing of polls at 10:00 p.m. with many still waiting to vote.
The results, however they may ultimately be counted, have cast the Westminster voting system (also used by Canada) into deep disrepute, creating a shocking imbalance between the votes cast and the results produced.
The outcome can only be considered a clear defeat for all three major parties.
The Liberal Democrats have been the biggest victims of the electoral system: Despite having attracted a share of the vote not much smaller than Labour's, Nick Clegg's party appears to have won only about a quarter the number of seats, because Liberal Democrat votes are distributed evenly across Tory and Labour ridings.
David Cameron's Tories, even if they prove the victors, won far below the strong majority they could have expected after three consecutive Labour governments and a terrible recession. Their message of a minimal-government "big society" did not seem to galvanize voters, and Mr. Cameron's last minute shift to the right delivered a strong shift of votes in England and Wales, but nothing near the nationwide shift in opinion that gave the Tories an 18-year hold on power after 1979.
And Mr. Brown's Labour Party came close to collapsing in disarray after their leader, who had never campaigned for the prime ministership before, floundered badly in the debates, delivered a dissonant message that combined a spending-driven economic rescue with right-wing populist messages on immigration and crime, and then seemed to implode after he was caught on microphone describing a voter as a "bigoted woman."
While the Tories were seemingly in a position to form a government, if their seats fall below the 326 needed for a majority it appeared that Labour may try to join forces with the Liberal Democrats and stay in power, under the argument that a majority of Britons have voted for a liberal or centre-left party.
"If you have an alternative of two parties which have a greater number of seats than the third [the Conservatives] then I don't know what else there could be considered … obviously we would be prepared to consider that," Peter Mandelson, Mr. Brown's most senior cabinet minister, said.
Ed Miliband, the Labour minister who wrote the party's manifesto, said early Friday morning that "those discussions [over a coalition]will have to take place between Gordon Brown and Nick Clegg."
So it seems that the conventions of the Westminster voting system, for the first time since 1974, have fallen apart to expose their most serious flaws.
And beneath this is a larger crisis that may take longer to resolve. The practice of two large parties taking turns occupying a wide swath of ideological terrain, long a mainstay in most English-speaking countries, has itself dissolved, creating a new logic of political strategy.
After Mr. Clegg attracted a huge following in the wake of Britain's first televised debates, both Labour and the Tories seemed to panic and flee from the centrist, big-tent platforms that had seemed safe bets for the election.
After a lengthy period of apparent voicelessness, Mr. Brown returned to form in the final days of the campaign, delivering rousing rallies with a decidedly partisan message of left-wing Fabianism, a new and risky message that seemed to give him momentum.
Likewise, Mr. Cameron all but stopped mentioning his "big society" message of volunteerism, local democracy and worker ownership, returning to a more conventional right-wing voice of tax cuts and attacks on government spending - again, rallying his supporters.
This, in effect, marked the end of a 15-year experiment in "third way" politics, leading to a new, mysterious period in British politics in which there is no clear middle ground.
With files from Reuters