'The Labour party today stands in the best tradition of modern social democracy', he said.
'There are also people in the Liberal Democrats who are modern social democrats'.
In a BBC interview he also added the UK should not be afraid of finding better ways of making 'our politics work'.
The Guardian (p14) reports Lib Dem MPs have received floods of telephone calls and emails from party activists and councillors 'who fight Labour harder than they do the Tories' in their towns and cities.
One senior MP said: 'Councillors are saying 'why are you co-operating with them when we are fighting them?''.
And Association Liberal Democrat Councillors director Howard Sykes said: 'There's great concern and anxiety among activists and members about the annoucnement and the policies which are being pursued.'