The union, USDAW, which is a shop worker’s union whose clients include Tesco, said Mr Starmer was “someone who can persuade voters that they have what it takes to be a Prime Minister”. The union also said they support Angela Rayner as its deputy leadership candidate. The nomination now leaves three of the main five Labour unions left to nominate a candidate.
To remain in the race, Jess Phillips and Emily Thornberry will now need the backing of five percent of local Labour groups (CLPs) to demonstrate that they have the support of the membership.
Local associations will both face strong resistance from Momentum.
The group is a Corbyn-supporting campaign which has organised to back its candidate in previous leadership contests.
Ms Thornberry has a solid track record in Mr Corbyn’s team which should work to her advantage.
Ms Phillips’ own record as a moderate backbencher and opponent of Mr Corbyn’s leadership will make her less popular with many members.
The bad news for Ms Phillips’ campaign came as she hit out at the “patronising” notion that working class credentials is the most important characteristic to replace Mr Corbyn.
She wrote on the Mumsnet website: “We all have different life experiences.
“I find trying to prove where you come from as if that is all that matters to the voters a bit patronising.
“I think it’s what you do and how you live now that matters.”
It comes as the Birmingham Yardley MP condemned her own performance at the first regional hustings event in Liverpool on Saturday.
The backbench MP described the format of the event as “ridiculous” as each of the five candidates were given just 40 seconds to answer a question.
She admitted her responses “fell flat”. Ms Phillips wrote in The Guardian: “The hustings was awful. I was awful because I was trying to hit a million different lines and messages in 40 seconds.
Ms Phillips said: “I might not look the most like a Prime Minister in this race, because apparently looking like a prime minister is a thing.
“I cannot win that war, so I am going to stop fighting it. I am going to do the thing that made tens of thousands of people ask me to run to be the leader. I am going to say what I think. I am going to give honest answers.