Labour's pursuit of a "Middle England" agenda has meant it is neglecting its core working class supporters, a former adviser to Tony Blair has warned.
Too much attention is paid to marginal seats, says Mr Cruddas
Jon Cruddas said this was not a criticism of his former boss, but the product of the electoral system.
The Dagenham MP, in No 10 between 1997 and 2000, said too much policy was based on the "preferences and prejudices" of focus groups.
He said this was to the detriment of working class people in his community.
Mr Cruddas was speaking out as Labour delegates headed to Brighton for their annual party conference.
He argued that the problem was the electoral system pushed all three mainstream parties into fighting over the same political terrain.
"The debate is whether that is good for democracy or whether it disenfranchises huge swathes of the country, including working class communities in my constituency," he said.
"My view is they have less political currency than middle class swing voters which means, arguably, those most in need have less priority for a Labour government.
"The question is, is this the only form of Labour government that this electoral system can achieve?
"Can one emerge which reflects all different elements of the Labour coalition and not just the centrist ones?"
Mr Cruddas said most focus groups concentrated on "the preferences and prejudices of the swing voter and they might be different from non-swing voters".
The working classes did not have "as much traction as other communities in this country", he said.
"The dominant priority for my community is low rent social housing - that is not a priority for focus group members," he said.
"Choice in public services is actually a fiction to the people I represent - It doesn't mean anything. You haven't got a baseline of public services from which they can choose."
However, Mr Cruddas had praise for the government's public service reform agenda, although he conceded it was "not going fast enough - it never can, but there are positive things around".
Last week he joined a government minister to open one of eight integrated health centres in his borough, which was the result of a "radical partnership between the public and private sector", he said.