What does Momentum’s backing for Rebecca Long-Bailey mean for her leadership hopes?

The endorsement of the Corbyn-supporting group is worth more than the numerical total of its members’ votes, writes John Rentoul

Momentum constitutes about a tenth of the Labour Party’s membership (Getty)

Momentum, the group of Jeremy Corbyn supporters in the Labour Party, has declared Rebecca Long-Bailey its favoured candidate for the leadership.

This is an important boost for her campaign, but hardly decisive and certainly not unexpected. Momentum is not as powerful as it once was. It was formed in the wake of Corbyn’s election as leader in 2015 by Jon Lansman, who ran that campaign, and who had an email database of its supporters.

For the past four years, Momentum has dominated the internal democracy of the party, running a slate of candidates for those National Executive Committee places that are elected by Labour members.