Labour has opened its biggest opinion poll lead since the general election as the Conservatives struggle to recover from the aftershocks of the much-criticised Budget, according to the latest "poll of polls" for The Independent.
It puts Ed Miliband's party at its highest support since he became leader, suggesting Labour is continuing to reap the benefits of the anti-Tory backlash since the Budget in March.
The findings make grim reading for the Liberal Democrats, who have slipped to their lowest level since the Coalition's creation, having lost more than half of their backing since the election in 2010.
With the Commons returning today, senior Conservatives hope to regain the initiative over the next few weeks following the decision by the Chancellor, George Osborne, to ditch several of the Budget's most contentious measures.
Mr Osborne faced fierce criticism earlier this month after making three Budget U-turns in four days, culminating with a decision to scrap the controversial "charity tax" proposal.
Ahead of his potentially embarrassing appearance at the Leveson Inquiry today, the Chancellor yesterday attempted to get back on the front foot over the economy, issuing his most strongly worded message yet to leaders of eurozone nations and expressing his exasperation at their continued failure to find a solution to a crisis that he said is hampering Britain's own chances of economic recovery. Like David Cameron, he has sounded a more Eurosceptic note in recent days – a move they hope may attract disillusioned Tories back from the UK Independence Party.
Meanwhile, Theresa May, the Home Secretary, also came out fighting yesterday, setting herself at loggerheads with judges over a planned clampdown on foreign criminals that is likely to play well with the Tory base.
Labour's support rose to an average of 42 per cent last month, with the Conservatives on 34 per cent and the Liberal Democrats on 10 per cent.
An eight-point lead would be enough to deliver a handsome Commons majority of 80 for Mr Miliband in an election fought on the proposed new constituency boundaries.
By contrast, the Liberal Democrat parliamentary party would come close to being wiped out, holding on to just 10 of its 57 seats.
The only consolation for the Tories is that their support recovered marginally in May – despite a succession of U-turns over Budget measures and damaging revelations at the Leveson Inquiry – after a steep fall in April.
John Curtice, Professor of Politics at Strathclyde University, who compiled the weighted average of surveys conducted by ComRes, ICM, YouGov and Populus, said the polls showed continuing declines in the popularity of both Mr Cameron and Nick Clegg. Mr Miliband still suffers negative ratings but is less disliked than the two Coalition leaders.
He has returned to the level of popularity he last achieved last summer after the hacking scandal was exposed.
Professor Curtice said there was also some evidence of Labour finally beginning to make progress in convincing voters of its economic competence, although the Cameron/Osborne/Clegg team is still rated higher on the issue than Mr Miliband and the shadow Chancellor Ed Balls.
"The next few months could well prove crucial to Labour's hopes of returning to power in 2015," Professor Curtice said.
"The public now has doubts about the quality of the leadership and government being provided by both parts of the Coalition and seems prepared to take a fresh look at the alternative on offer from Labour.
"The party needs to seize this opportunity to generate positive enthusiasm for the prospect of a Labour government run by Ed Miliband.
"If it can, it might succeed in establishing a poll lead that proves durable in the face of any future restoration of the Coalition Government's political fortunes.
"If not, then Labour might well find that all too rapidly its poll lead is once more pegged back again and the prospect of an overall majority in 2015 looking like a distant dream."