Tower Hamlets has been hailed a "battleground borough" by Labour ahead of this May's election with the party looking to attack Mayor Lutfur Rahman's record on housing and jobs.
Sadiq Khan MP, who is leading the party's strategy on London elections, listed the area as its key target for the heart of the capital.
Current London Assembly Member for City and East, John Biggs, is standing against Rahman, and Khan said the change in Tower Hamlets was needed to arrest deep problems in the borough.
"Tower Hamlets desperately needs a Labour mayor," Mr Khan, shadow minister for London, told The Wharf. "The independent mayor has failed to build the number of affordable homes Tower Hamlets needs and as a result home ownership and even renting is increasingly out of reach for most residents.
"He has failed to create enough jobs and apprenticeships. In John Biggs, Labour has a fantastic local candidate, with the experience needed to build more affordable homes and create more jobs and apprenticeships."
Mr Khan said the party was focusing its efforts on Tower Hamlets - one of six borough's on Labour's target list and the only one in inner London - for the May 22 council and mayoral elections.
Tuesday saw activists calling residents in Tower Hamlets to tell them about Mr Biggs' hopes for the borough.
"Tower Hamlets is a Battleground Borough, which means we will be supporting John in every way we can," said Mr Khan.
"Next Thursday London Labour MPs will be in the borough going door-to-door to talk to residents. We will campaign day and night."
In response, Cllr Rabina Khan, cabinet member for housing said: "Tower Hamlets is building more affordable homes than anywhere else in the UK - as evidenced by the £50million the government has given us in the shape of the New Homes Bonus.
"Since 2010, we've created over 1,750 apprenticeships and training posts, 2,750 jobs and nearly 4,000 Olympic jobs.
"Sadiq has clearly been spending too much time with the Tower Hamlets Labour Party who left the respectable mainstream - and the facts - behind a long time ago."