An opinion poll suggests that Britain's opposition Labour Party has taken a three percentage point lead over Prime Minister David Cameron's Conservative party.
The Survation poll for the Mail on Sunday newspaper indicates that Labour support was on 34%.
It indicated that Conservative support stood at 31% and support for the anti-European Union UK Independence Party was at 17%.
The Liberal Democrats were on 8%, the Greens on 4% and the Scottish National Party were on 5%.
The election could determine Britain's place in the European Union and Scotland's future in the United Kingdom.
It is the closest since the 1970s with neither of the two main parties able to open up a big enough lead to rule alone.
The pollster surveyed 2,128 people online from 1 May to 2 May.
Elsewhere, The Sunday Times, YouGov opinion polls suggests that Britain's conservatives are leading at 34%.
It suggests that Britain's Labour Party has 33% of support.
The Liberal Democrats are indicated by the poll to have 8% of the vote with the Green Party trailing with 5%.