Labour has established a double-digit lead over the Conservatives and the Liberal Democrats have been overtaken by the UK Independence Party, according to a latest poll.
The YouGov survey for The Sun put Labour 11 points ahead, on 43% to the Tories' 32%.
It also found that Ukip, with 9% support, had pushed the Lib Dems, on 8%, into fourth place.
The findings follow a torrid month for the Tory-Lib Dem coalition, which has faced heavy criticism over the Budget and its handling of the threat of strikes by fuel tanker drivers.
A second poll showed Labour extending its lead over the Tories to nine points.
Support for Labour had risen by 4% to 42% over the past month, while that for the Tories had fallen one point to 33%, the Populus survey in The Times found.
The Liberal Democrats were unchanged on 11%
Populus also found that 61% of voters felt the coalition was doing "badly", up from 51% in September. Some 24% said the coalition was doing "very badly", up from 15%.
:: YouGov surveyed 1,783 British adults on April 15 and 16. Populus interviewed 1,003 people by telephone between April 13 and 15.
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