The Liberal Democrats ought to be doing better, deputy leader Vince Cable has said.

With Gordon Brown facing difficulties on a number of fronts, Cable said the Lib Dems should be riding higher in the polls.

An ICM poll for the Sunday Telegraph put the Lib Dems on 20 per cent, which Cable said was lower than he would like.

Released days before local elections in England and Wales the survey puts the Tories on 39 per cent, Labour on 29 per cent and the Lib Dems on 20 per cent.

Cable told BBC1's The Politics Show: "We are not doing as well as we hoped we would be, I'm not complacent.

"We can do better and should do better. There is a big opportunity - we are not doing badly but we could do a lot better."

The Lib Dem Treasury spokesman made no reference to Nick Clegg's leadership since he took over in December and apportioned some of the blame to himself.

He said his party had to work harder to demonstrate its credibility with voters.

"I think it's a question of us putting in more work, being credible on the issues that really matter to people," he.

"A lot of responsibility comes onto me because the thing people are worried about more than anything is the economy."