Opinion polls today indicated Britain remains on course for a parliament with no outright majority, raising the rare prospect of a minority or coalition government after Thursday's election.
Conservative Party leader David Cameron had claimed to have the momentum after a strong performance in last week's leaders' television debate.
However, surveys today indicated his party's lead has been pegged back to 5 percentage points - as much as half its weekend advantage - and suggested either the Conservatives or prime minister Gordon Brown's Labour Party could still win.
The quirks of Britain's electoral system, where seats are allocated purely by constituency results, and not in proportion to the overall share of the vote, mean that Labour could come third in the popular vote but still remain the largest bloc.
The race has been blown wide open by a strong showing from the Liberal Democrats, traditionally Britain's third party, whose own leader, Nick Clegg, has challenged Mr Cameron's claim to be the candidate of change.
If the polls were replicated nationwide on Thursday, it would result in a "hung parliament" where no single party has an overall majority, a result last seen in Britain in 1974.
The uncertainty could unsettle markets who want swift action to tackle a budget deficit running at over 11 per cent of GDP, although the currency and foreign exchange markets have so far taken the growing prospect of a hung parliament in their stride.
Today's ICM/Guardian poll had the Conservatives on 33 per cent, five points ahead of both Labour and the Lib Dems, with the Conservatives the biggest party in parliament.
The daily YouGov/Sun poll put the Conservatives on 34 per cent, the Lib Dems on 29 per cent and Labour on 28 per cent, this time with Labour the biggest party.
Reuters