Here is the full text of John McDonnell's statement, launching his leadership bid.
It is becoming increasingly apparent that Tony Blair will announce his resignation as Leader of the Labour Party over the next 12 -18 months.
Some have argued that instead of an open democratic election for the leader of the party, there should be a smooth transition or virtual coronation of his successor.
This would deny party members the opportunity of openly debating the issues facing our party and the future direction of the country.
An election for the Leader of the party will allow for a democratic debate on the future of Labour.
Therefore following increasing demands from various sections of the movement, I have decided to declare myself as a candidate for the leadership of the Labour Party as soon as the present incumbent retires.
To be clear this is not a so-called "stalking horse" candidature but a serious challenge for the leadership of the party when a vacancy occurs.
I am standing to ensure that thousands of Labour Party members and supporters have the chance to participate in deciding not only who should be the next leader of our party but more importantly what policies the party should be pursuing.
There are many that feel the party has lost its way. Many of the policies being pursued in Government have broken up the broad coalition of support Labour has relied upon throughout its history to bring it to power.
New Labour has systematically alienated section after section of our supporters - teachers, health workers, students, pensioners, public service workers, trade unionists and people committed to the environment, civil liberties and peace. Spin and allegations of sleaze are causing decent people to lose trust in our party.
This is reflected in lost votes, lost elections, lost members and a Labour Prime Minister having to rely upon Conservative votes in Parliament to force through legislation.
There are growing calls from across the party for change. We need to rebuild a progressive consensus, inspiring and giving people hope that another world is possible. We need those who have turned away from Labour to come back home.
For the first time in decades people no longer feel they have a political voice. This campaign is a challenge to the present political consensus.
I will now seek support from all sections of the movement. At next Saturday's conference of the Labour Representation Committee we will debate the policies needed by a real Labour government and the way in which we can reinvigorate democratic participation in the party.
From September this campaign will be travelling the country, convening meetings face to face with party members, supporters and the general public to discuss the issues facing us. We will be urging those thousands of Labour Party members who have left the party to rejoin and those who are no longer active supporters to re-engage.
We are launching a campaign web-site today and we will use every possible means of communication and new technology to stimulate this debate and get our message across.
The campaign will be waged in an open, comradely and friendly manner based upon a debate on the policies not personalities.
Let the debate begin.