Sir Keir Starmer has become the first Labour leadership contender to be guaranteed a place on the final ballot paper after winning the support of retail union Usdaw.

The shadow Brexit secretary said that if he was elected as Labour leader, the party “will stand shoulder to shoulder with the trade union movement as we take on the Tories and rebuild trust with working people”.

He won his place on the final ballot after adding Usdaw’s endorsement to the support of Unison and the Socialist Environment and Resources Association (SERA).

Candidates are required to have won the nomination of three Labour affiliates, including at least two unions, which amount to at least 5% of affiliate members.

The only other route on to the ballot is by receiving nominations from at least 5% of constituency Labour parties (CLPs).

Sir Keir said: “I’m honoured to have received Usdaw’s endorsement for the Labour leadership.

“Our campaign is building unity across the labour movement, amongst trade unionists and members.

“Usdaw represents over 400,000 workers and fights every day for its members and for a fairer society.

“If I’m elected leader, Labour will stand shoulder to shoulder with the trade union movement as we take on the Tories and rebuild trust with working people.”

Usdaw also backed Angela Rayner for the deputy leadership role.

The union’s general secretary Paddy Lillis said: “The Labour Party must be led by someone who can persuade voters that they have what it takes to be a prime minister and we are a government in waiting.”

The deadline has now passed for people to join Labour to vote in the leadership contest, which will end with the announcement of the winner on April 4.

Shadow business secretary Rebecca Long-Bailey, shadow foreign secretary Emily Thornberry and backbenchers Lisa Nandy and Jess Phillips are still in the race to join Sir Keir on the ballot.

Stepping up her campaign for the leadership, Ms Phillips said the party must stop trying to appease “fear-mongering opportunists” who sought to whip up opposition to immigration.

Ms Phillips said Labour needed to challenge the “pernicious myth” that working class communities were hostile to immigration.

Lebour leadership election timetable
(PA Graphics)

She said Labour needed to be clear that it did not believe the numbers coming to settle in the UK were too high.

Writing in The Independent, Ms Phillips called for a series of reforms to a system she described as “one of the cruellest and maddest parts of government”.

She said people who had lived in the country for many years and have families in the UK should be able to stay without fear of being pursued by the Home Office.

Ms Phillips also called for an end to the practice of immigration detention and the deportation of child refugees when they turned 18.

“For too long, we have allowed this debate to be dominated by fear-mongering opportunists: Nigel Farage standing in front of a poster featuring refugees and the words ‘Breaking Point’; Michael Gove whipping up fear of mass migration from Turkey,” she said.

“In an attempt to sound tough, Labour has sometimes been too slow to stand up against this kind of rhetoric and, in the worst cases, even been seen to appease it.

“The most pernicious myth we have failed to bust is that working-class communities are hostile to immigration, which means that middle-class politicians must watch their language or, worse, pander to this perceived prejudice.

“This then leads to political arm-wrestling between the left and the right over who can sound the toughest on immigration. Why, when we’re asked whether immigration is too high, do Labour politicians so often fumble their response? Let’s say what we think: no, it isn’t.”

Earlier, in a webchat on the Mumsnet website, Ms Phillips hit out at the idea that having a working class background was all that mattered in the contest to succeed Jeremy Corbyn.

“I find trying to prove where you come from as if that is all that matters to the voters a bit patronising,” she said.

The backbencher acknowledged it would be a “bold roll of the dice” for Labour members to elect her as leader.

But she said the nature and scale of the defeat the Labour Party suffered at the election meant “a genuine fresh face” was needed.

“A different approach. A bold roll of the dice. And I think that is what I am. And that that is the only way we can beat Boris Johnson.”