Labour is enjoying a huge 17% lead over the Tories in the wake of the cash-for-access scandal, according to a new poll.
A section of a ComRes/Independent poll taken after the row broke on Sunday saw Labour on 47% to the Conservatives' 30%.
The section of the poll conducted before the row broke out showed Labour up three points on 43% and the Tories down four on 33%.
Experts warned the sample conducted after the Sunday Times revelations amounted to a third of a 1,000 respondent data set, meaning it was well within the margin of error. But the Labour lead suggests the government has taken a serious knock after the Budget and that the cash-for-access row may taint its record with voters.
The poll found two-thirds of voters (66%) believed the measures in the Budget showed the Conservatives "are the party of the rich".
The Budget may also have dented the government's support among older people – a key demographic due to the reliability of their vote.
Labour enjoyed a substantial lead among 55- to 64-year-olds and the Tory lead had been reduced to single digits among the over-65s. The erosion of their advantage among these groups is likely to be a result of the so-called 'granny tax'.
A Populus poll for the Times showed a more modest four-point lead for Labour, with the opposition on 38% (down one) and the main governing party on 34% (down three).
But the poll contained similar criticisms of the chancellor's Budget last week, with 49% saying the scrapping of pensioner tax allowance was unfair and 53% saying the reduction of the top rate of tax to 45% would do "nothing" to help the economy.
There was little excitement at the attempt to lift low-earners out of income tax, with only 35% of voters saying they would be helped by the measure.
The David Cameron-George Osborne team continues to enjoy more confidence on the economy than the Ed Miliband-Ed Balls team, although there is evidence that lead is also starting to erode.
The Tory pair enjoy a 60% lead to Labour's 40%, down from 66% to 34% last month.