Labour is facing a crisis because of a long-term decline in its membership, one of the candidates for the party's deputy leadership has warned.
Mr Cruddas says Labour must shore up a fall in members
Jon Cruddas says Labour can be rebuilt from the grassroots but must change its ways and reconnect with the electorate.
Figures show Labour's membership fell slightly in 2005 to 198,026, half the number of members in 1997.
The Labour party's chairperson, Hazel Blears, said the figures had been used in a "sensational way".
But Mr Cruddas insisted Labour would have no members by 2013 if the same rate of decline which began in 2000 continued.
He suggested data indicates Labour has lost the equivalent of 27,000 members a year since the start of the decade.
"You are not going to resolve this from Westminster - you are not going to resolve this simply through edicts from the centre," Mr Cruddas said.
"You need to build it from the bottom up. Activity on the streets, a local presence, continuously year-on-year and not just at election times."
Ms Blears disputed Mr Cruddas's figures and said: "Our membership is broadly the same as other political parties, and not just in this country but around the world there is a lack of political engagement.
"And I think that the process we're undertaking to involve the public should also help us to reinvigorate our party politics - something that desperately needs to be done."
Labour has said membership, which peaked at 405,000 after Tony Blair came to power in 1997, fell by 3,348 in 2005. This was the lowest reduction of its kind since records began in 1991.
A review into political party funding is due to publish its recommendations in January.
Labour recently confirmed it was facing "acute cash flow problems" with debts of £23.4m.
BBC political correspondent Laura Kuenssberg said all the main political parties struggle to attract and keep members.
Our correspondent said the fall in Labour membership had put the party finances under even more pressure.