Ex-Downing Street aide Jon Cruddas has confirmed he will run for the deputy leadership of the Labour Party, if and when a vacancy arises.
Mr Cruddas worked at No 10 between 1997-2001
The Dagenham MP, 44, says he wants to distance the role of deputy leader from the deputy prime ministership.
"I think the deputy leader should be the voice of the party to the government," he told the BBC.
Other declared contenders for John Prescott's job include Alan Johnson, Peter Hain and Harriet Harman.
Mr Cruddas was Tony Blair's deputy political secretary between 1999-2001 and has been MP since 2001.
He said he was first approached by members of the party wanting him to stand a few weeks ago.
But he said it was only after talking to people at Labour's conference, that he became confident he could help the party reconnect and stand a good chance of victory.
Setting out his bid for the deputy leader's role, he said: "Reaching out to our people doesn't mean coming up with better sound bites and spin - it means coming up with better policies.
"We need to reaffirm our belief in collective action - through local communities, through public services, through strong and effective trade unions.
"In the election, there will be a choice: change or more of the same. I am standing because the party needs and wants to change.
"It's time to reach out again to our natural supporters, written off for too long.
"It's time for change - and I am the candidate who will deliver it."
Mr Cruddas was an assistant to two Labour general secretaries from 1994 before joining the prime minister's staff.
Despite his work for Mr Blair, he is seen as on the left of the party and has rebelled against the government over the imposition of university tuition fees.
He is a vocal opponent of the British National Party, which has tried to build a stronghold in his east London seat.
He has also criticised the prime minister for neglecting Labour's traditional working class constituencies in favour of those inhabited by the middle classes.
Mr Cruddas, who is married with a son, said he planned to open a campaign office within the next seven days and is expected to name the MPs, members and trade unions who back his bid in the coming weeks.
He says he plans to focus on building a grassroots network of activists in every constituency.