A long-standing Labour leader will find out today whether he faces the first internal challenge to his position in more than 20 years.
A challenge now hinges on the votes of union and affiliate members, which are due to be made public later today.
Sir Robin, 63, has said he welcomes an open contest and wants the party to be united for the local elections in May.
Labour councillor Rokhsana Fiaz has already declared that she wants to challenge him if members vote for an open selection.
Ms Fiaz, 47, was born and raised in the borough and has been a Labour councillor there since 2014. She told the Standard: “I want to offer Labour Party members in Newham a choice in who their candidate should be. There’s a strong alertness to there being one person at the top for 23 years now.”
She said she had been “impressed” by some of Sir Robin’s policies but added: “I think the world, and Newham, has changed quite significantly since our turnaround in the run-up to the Olympics. The climate facing many of our residents means that as a council we’ve got to up our game.”
It is understood two other councillors may be considering challenging Sir Robin for the mayoralty.
He served first as a councillor from 1982 to 1986 and then from 1992 to 1995, when he became leader of the council.
After a local referendum in 2002 he became the first directly elected Labour mayor in England. He was re-elected in 2006 and 2010. In May 2014 he won his fourth term in office.