London, England (CNN) -- The worst kept secret in British politics is now officially confirmed and the UK will go to the polls for a general election on May 6 to elect 650 members of the House of Commons.
It will be a far closer contest than many had expected a year ago. Then a huge lead for the Conservative Party, led by David Cameron, made it look a racing certainty that the Tories, as they are known, would be heading back to government for the first time since 1997.
The depths of the recession, the unpopularity of Britain's rather dour Prime Minister Gordon Brown and the parliamentary expenses scandals -- which the public seemed to blame more on the ruling Labour Party, although all were tainted -- had led to widespread predictions of a Conservative landslide.
But over the past few months the opinion poll gap has closed. As an election approaches people think less "Do I like the present government?" and more "Who do I trust to run the country for the next five years?" as they answer pollsters' questions.
Some Conservative policies unraveled swiftly on public presentation and, with unemployment and public debt decreasing faster than expected, the possibility of a "hung Parliament" (in which no party holds an overall majority) has been much talked about.
What many had forgotten was the extent of the electoral mountain the Conservatives have to climb in order to wrest power from Brown's Labour Party. To gain an overall majority of just one in parliament they have to gain an extra 117 constituency seats, a feat which no party has achieved since the 1930s. (At the last election Labour won 355 seats, the Conservatives 198 and the Liberal Democrats 62.)
The Conservatives tend to build up huge majorities in seats they win but do not spread their votes so well across the country. As a result they could score five points higher than Labour in terms of their share of the national vote and yet still see Labour returned with the biggest number of seats in parliament.
At the last general election in 2005, Labour had only a 36 per cent share of the vote nationwide but took 57 per cent of the seats in parliament. A narrowed gap in opinion polls over the previous two months showed the Conservatives with 37 per cent of the vote and Labour with 32 per cent (although Tory tax cut promises seem to be widening the gap again as the poll date approaches). An election result with those figures could still give Labour 294 seats to 277 for the Conservatives.
Such a result could bring into play the third party in British politics, the Liberal Democrats, led by Nick Clegg and including the respected economic spokesman Vince Cable. The system hits them particularly hard: the Lib Dems scored 23 per cent of the vote at the last election and got only 10 per cent of the seats.
What would be the impact of a hung parliament on the UK?
Either of the major parties might need the Lib Dems' support to govern. But that puts Clegg in an unenviable position. If his party were to help Brown to cling to office after an apparent rejection by an electorate no longer prepared to vote Labour in with a governing majority then he would get little thanks.
But with the Lib Dems as the most pro-European party in British politics it is virtually impossible for him also to support a Conservative administration which will be the most virulently Euroskeptic in British political history. (The Conservative Party has turned its back on the center-right mainstream in Europe -- the European Peoples Party backed by Chancellor Angela Merkel in Germany and President Nicolas Sarkozy in France -- and allied with a small group of maverick right-wingers from Poland and the Czech Republic).
Clegg has said that the British people, not his party, will be the kingmakers, insisting: "Whichever party has the strongest mandate from the British people it seems to me they have the first right to try and govern". But he has not said whether he means the party with the biggest share of the vote or the party with the biggest number of seats. The Liberal Democrats will be fighting to win seats off Labour in the north of England and seeking to defend their own seats from the Conservatives in the south-west.
As so often, the key issues in the election will center on the economy. Gordon Brown was chancellor of the exchequer (chief finance minister) for 10 years before he succeeded Tony Blair as party leader and prime minister. The Tories are assailing his record as chancellor and blaming him for the recession. But some voters are nervous of entrusting the conduct of the economy to the comparatively youthful David Cameron and his shadow chancellor, the 38-year-old George Osborne.
Labour argue that the Conservatives showed their inexperience by opposing virtually all the measures Brown and his chancellor Alistair Darling took to meet the banking crisis, measures which became a model for many governments around the world. They also suggest that the Conservatives would imperil the recovery by starting to cut government expenditure too soon.
What most economists agree is that whichever party wins the election, or shares power after it, Britain faces a period of economic woe, with taxes rising and government expenditure and borrowing having to be cut back.
Both major parties have been tainted by recent scandal. The Conservatives have been embarrassed by revelations that their vice-chairman Lord Ashcroft, a billionaire who contributes significantly to their party funds in marginal seats, appears to have gone back on promises to become domiciled in Britain rather than Belize and to pay his taxes in the UK.
Labour has suspended three former Blairite cabinet ministers -- Stephen Byers, Patricia Hewitt and Geoff Hoon -- after they were caught in a TV and newspaper scam touting their services as lobbyists to the highest bidder.
A key question is whether many people will turn out to vote after both those revelations and the scandal over MPs' expenses which led to public ridicule of parliament. The turnout in 2005 was 61.4 per cent of those entitled to vote. Some psephologists fear it could even drop below the record low of 59.4 per cent in 2001.
This will, however, be an election with a difference. For the first time ever in Britain there will be a series of three live television debates between the three major party leaders. That could boost turnout. It is certainly likely to have a major effect on the contest.