How to get rid of the leader

Under Labour party rules, 20 per cent of the Commons members of the Parliamentary Labour Party - 71 MPs - are needed for a valid challenge.

Gordon Brown could decide to stand down in the face of such a challenge and not fight a leadership election.

But if the leader is Prime Minister and refuses to resign, then an election can only proceed if it is requested by a majority vote at a party conference.

Then an electoral college of unions, MPs and party members would vote on each candidate. Each group has a third of the vote and each member has one vote to cast.

Constituency parties and unions would normally ballot their members on the candidates in order to represent their views when they vote.

A series of postal ballots would then be held.

If Mr Brown chose to resign in the event of a leadership bid then the party would have to appoint an interim leader.

This could be the deputy leader but the final decision would be made by the Cabinet. Mr Brown could also remain as a caretaker until the end of a contest.