The public's support for the Liberal Democrats has tumbled sharply since George Osborne set out the coalition government's austerity budget, an opinion poll for The Independent discloses today.
The ComRes survey shows backing for Nick Clegg's party at a post-election low.
The budget package appears to have boosted support for the Conservatives, who stand on 40 per cent, a rise of four points since a ComRes poll for the Independent on Sunday on 20 June. Labour is up one point at 31 per cent, while the Liberal Democrats are down five points at 18 per cent.
The other parties are unchanged on 11 per cent, which includes 3 per cent for the UK Independence Party and 2 per cent for the Green Party.
Some Liberal Democrat MPs fear their party is being used to provide cover for Tory-led plans to cut spending and raise taxes in the drive to reduce Britain's huge deficit.
They will point to today's finding that only 68 per cent of people who voted for the party last month said they would do so again. This support is more likely to go to Labour than the Tories, the ComRes survey found.
The Conservatives will be relieved that they still seem to be enjoying an electoral honeymoon with the voters despite the grim economic medicine being handed out by the coalition.
Indeed, repeated in a general election, the level of support for the parties would give David Cameron a narrow overall Commons majority of 12.
The party now has 49 per cent support among the over-65s and is ahead of Labour in every age group apart from 18 to 24 year olds. It has achieved a marked increase in support among 25 to 34 year olds, chiefly at the expense of the Liberal Democrats.
The poor Liberal Democrat showing is in line with two weekend polls that put the party on 16 per cent, compared with the 23 per cent it achieved at the general election. The party's support seems to have been hit by the decision to raise VAT to 20 per cent in January – just seven weeks after it vigorously opposed the policy at the election.
Mr Clegg will come under pressure at the Liberal Democrat conference in September to reassure delegates that the party's identity is not being subsumed in the coalition.
The poll of polls
Conservatives: 40 per cent (+4)
Labour: 31 per cent (+1)
Liberal Democrats: 18 per cent (-5)
Others: 11 (-)
ComRes telephoned a random sample of 1,003 GB adults on 25-27 June, with data weighted demographically and by past vote. ComRes is a member of the British Polling Council and abides by its rules. Full tables at www.comres.co.uk