The survey of more than 6,000 voters puts Ukip on 27 per cent, Labour on 26 per cent, the Conservatives at 22 per cent, the Liberal Democrats on nine per cent and the Green party projected to get 10 per cent.
However, the distribution of Ukip voters means pollsters expect its winning overall vote share may not translate in practice to a majority of UK MEPs.
Nigel Farage’s party is however projected to emerge tomorrow with between 21 and 23 members of the European Parliament (MEPs), a huge increase on the 13 it won in 2009. Labour is projected to win between 21 and 25.
The forecast suggests that the ballot will return between 14 and 17 Conservative MEPs, and Liberal Democrats are braced for being wiped out. Even with two or three seats, Lib Dems will have fewer than the Green party, an embarrassing drop from the 11 won in 2009. The poll was conducted by YouGov for the Sun.