Members of the CWU union have voted unanimously to support the Labour Party and its leader Jeremy Corbyn in the general election on 8 June.
But delegates to its conference in Bournemouth voted against calling a mass anti-Tory demonstration in the run-up to the election.
Postal workers also discussed whether to vote on strikes against Royal Mail’s attack on their pensions.
The CWU passed an emergency motion on Sunday to campaign for a “Labour government, led by Jeremy Corbyn, that delivers a new deal for workers and their families”.
Conference delegates spoke about the need to kick out the Tories, and motions condemned Tory attacks on the NHS and disability benefits.
One speaker called for “a Labour government led by Jeremy Corbyn to reverse the cuts the Tories have inflicted on ordinary people”.
In a video message general secretary Dave Ward, who is not at conference due to illness, said, “Let’s get behind Jeremy Corbyn, let’s get behind John McDonnell and the leadership of the Labour Party.”
Acting general secretary Tony Kearns said Corbyn’s claim last week that Labour would not “play by the rules” was “absolutely right”.
He told a fringe meeting, “What happened in the past when Labour played by the mainstream media and right wing’s rules is it lost.
“We need a different and radical approach.”
Yet he spoke on behalf of the union’s national executive council against the motion that called for a demonstration. Kearns said there wasn’t enough time for a demonstration, and that it would be a “distraction” from campaigning for Labour.
Arguing for a demonstration, delegate Austin Goldsmith from Eastern No. 5 branch said, “Carrying this motion will send a message to the Tories—we will oppose you and we’re not going away.
“Dave Ward said this morning that we need to believe in the struggles we face. Carrying this motion will go some way to doing that and take the fight to the Tories.”
The motion was defeated overwhelmingly. Kye Dudd from Bristol branch said, “We shouldn’t be wasting our time having a rally in London with people who agree they’re voting for Jeremy Corbyn.”
But it will take more than door knocking for Labour to beat the Tories. It will take struggle on the streets and in the workplaces.