Alan Johnson has confirmed that he plans to stand for the Labour deputy leadership.

Following his endorsement of Gordon Brown to become the next party leader, the education secretary used an open letter to Labour members on Friday to set out his stall for John Prescott's job.

"I am not putting myself forward for leader - not least because there's a more experienced and obvious candidate," the former union leader said.

"But I will be able to assist, support, cajole and complement the person who carries the heaviest of all political burdens."

Johnson had been touted as a potential challenger to the chancellor for the full leadership.

But he insisted that his ambition, which he first indicated earlier in the year, had always been to be number two.

"I made it clear - in fact I think I said before anyone else - that my interest was in the deputy leadership," he told the BBC on Thursday.

"That's the job I want to focus on. I think it's an important job. I think it's crucial to have a leader/deputy leader team."

The deputy must be "subordinate to and supportive of the leader, [carrying] out whatever duties the leader sees as being essential to securing a fourth term in office," he said in his letter. 

"As someone whose background, foreground, mainland and hinterland are working class, I joined a party which understands that in order to effect change, it must not become a narrow class-based organisation.

"We have been at our most successful when we have signalled our determination to win political power by building an alliance of all sections of society."