Keir Starmer won the support of almost half the local Labour parties that backed Jeremy Corbyn in the 2016 leadership race, despite pleas from allies of the outgoing leader encouraging them to nominate Rebecca Long-Bailey.
The 648 constituency Labour parties (CLPs) have until midnight on Friday to formally endorse a candidate.
After CLP nominations closed, Starmer won 141 of the 285 CLPs that backed Corbyn over challenger Owen Smith in 2016. Some 103 voted for Long-Bailey.
Yet Momentum, the pro-Corbyn grassroots campaign group that helped propel him to victory in both 2015 and 2016, had backed the shadow business secretary, saying she was the “heart of a new and diverse generation of socialists who recognise that we cannot return to the politics of the past”.
The organisation has attempted to mobilise its activists to help Long-Bailey win key leadership nominations from CLPs across the country. The Salford and Eccles MP also has the support of leading Corbyn allies including shadow chancellor John McDonnell and Unite general secretary Len McCluskey.
Corbyn has not formally endorsed any candidate. But he has heaped praise on Long-Bailey, describing her as “our candidate for leader” and thanked her for her “steadfast” support during the attempted coup in 2016.
She told supporters on Friday the party could not win the next election if it veers away from the left-wing path set by Corbyn.
Labour suffered its worst election defeat since 1935 when it lost 59 seats in the December poll, a result that ushered in the first unequivocal Conservative landslide since the 1980s.
But Long-Bailey said the party must not row back from the “popular” policies found in its manifesto but instead learn to explain them better.
In an interview with HuffPost UK earlier this week, she also attempted to outflank Starmer on the left by pledging to keep Corbyn’s policies on taxing the rich, banning arms sales, tackling climate change and ending the gender pay gap.
Friday also saw the TSSA union, which housed Momentum’s office, back Starmer.
The result of the vote by party members is due to be announced on April 4.