But the long-touted future leader will still have to go through the gruelling internal selection process.
The party is determined hold a leadership contest to distance it from the accusations of shady back-room deals that surrounded the Blair-Brown handover.
Tony Blair changed the block voting rules that gave the unions an inordinate grip on the party, but the candidates will still have to win over grass roots party members, who are each entitled to an equal vote.
The candidates also have to be cleared by the party’s national executive committee before they are awarded the seat at the helm.
The leadership is usually announced at the annual party conference – with Labour next slated to meet in September. However, it is likely the party will call an extraordinary meeting as it would be logistically difficult for Brown to hang on that long after announcing his departure.
It is expected, although not necessary, that Harriet Harman’s deputy position will also be up for grabs.