Support for the Liberal Democrats has been damaged by their decision to form a coalition government, with most voters no longer knowing what the party stands for, a new poll has found.

The latest ComRes survey for the Independent put support for Nick Clegg's party down two points at 16 per cent, the Lib Dems' lowest rating in a ComRes poll since early April. The Conservatives are down one point to 39 per cent, with Labour up two to 33 per cent. If repeated at the election on a uniform swing, the latest figures would leave the Tories 10 seats short of an overall majority.

The poll also found that 73 per cent of voters agree with the statement that it is "difficult to know what the Liberal Democrats stand for", an increase of eight points since a ComRes poll on 2 June.

Fewer than two-thirds of people (63 per cent) who voted Lib Dem at the election would do so again now, compared with 94 per cent for the Tories and 92 per cent for Labour.