When UK voters head for the polls on May 6 it will be for the first time since 2005, when the Labour Party enjoyed its third successive election victory under Tony Blair.
This time the contest is likely to prove much closer. The Conservatives, led by David Cameron, have led opinion polls for much of the past year -- although recent months have seen a comeback of sorts for prime minister and Labour leader Gordon Brown.
Observers believe this election is likely to be the closest since 1992, when the Conservatives were returned to power. For that reason the Liberal Democrats -- known as the "third force" of UK politics -- may have a crucial role to play after election day in helping either party secure a parliamentary majority.
On a more localized level, smaller parties, as well as national parties in Scotland, Wales and Northern Ireland, are likely to have an impact on voters in their constituencies.