Jeremy Corbyn received a boost in the Labour leadership contest today when he won the backing of postal union the CWU.

The 190,000 strong union said it is backing Corbyn to stay on because he is a “leader for the millions, not the millionaires”.

CWU cited Corbyn’s anti-austerity stance as it said it would formally nominate the incumbent in the contest against Owen Smith, following in the footsteps of ASLEF, the train drivers’ union.

The move has been expected for some weeks because CWU – which represents workers in the postal system, telecoms and financial services – backed Corbyn in last summer’s contest.

Today Dave Ward, general secretary, said Corbyn’s plans for working people would help transform the country.

“We need a fundamental change in Labour politics and Jeremy Corbyn recognises this. He is the candidate to drive through the change that ordinary people are crying out for – opposing damaging austerity measures and tackling the housing crisis which is causing misery for so many.

“It’s policies like Jeremy’s announcement on extending the recognition for trade unions which we believe will make a real difference to the working lives of millions. Jeremy is a leader for the millions, not the millionaires, and the CWU is proud to support him.”

Smith, the sole challenger to Corbyn, has also put an anti-austerity agenda at the heart of his campaign but has not so far accumulated a raft of trade union endorsements.

Earlier this summer, at the height of the coup against Corbyn, the heads of 10 of Britain’s largest trade unions published an open letter calling on MPs to “respect the authority” of the Labour leader.