The chatter in the party has been that Watson runs around the country making sure 'his' people get chosen as candidates.
Douglas Alexander, who ran the 2010 campaign, is the frontrunner.
Read the full text of the Labour MP's resignation letter to Ed Miliband.
An interview with the Yale political scientist behind Ed Miliband's big idea.
Privileges and patronage are wired into the party's institutions. Falkirk is merely the latest example.
While the Labour leader takes time to ponder the future, his party is drifting into a style of politics that looks in urgent need of consignment to the past.
By choosing to answer the question "who runs Labour?" the Unite general secretary has suggested the answer was in doubt.
Activists shouldn't be dismissed as 'naïve' or 'immature' for expecting politicians to deliver on party policy.
Of the 14 Labour constituency parties placed under "special measures", just one, Falkirk West, was due to concerns over activity by Unite.
The electoral system, UKIP and the strength of the Labour brand all mean that the party is still likely to be the largest after the next election even after a fall in support.