The Socialist Workers Party (SWP) has decided to support grassroots socialist challenger Ian Allinson in the Unite union’s upcoming general secretary election.

Allinson has led a series of strikes at his workplace, Fujitsu in Manchester. He has also made the defence of immigrants’ rights and free movement of labour central to his campaign.

Current general secretary Len McCluskey triggered the election by resigning last month. It is the second time he has called a snap election to help himself hold the position as long as possible.

McCluskey is a towering figure on the Labour left, and the right is eager to topple him.

Regional official Gerard Coyne is the candidate of the Labour right and the bosses’ Financial Times newspaper. He wants to distance Unite from Jeremy Corbyn’s leadership, and calls for tough immigration controls.

Many socialists will wish to defend McCluskey’s leadership to prevent such a step backwards. In his campaign video McCluskey boasts of leading a “fighting back union” to galvanise that support.

But his reign has too often been defined by manoeuvres and compromises.

Unite wasn’t much of a fighting back union when Grangemouth boss Jim Ratcliffe put a gun to workers’ heads, or when Tata Steel prepared to throw whole steel plants on the scrapheap.

It’s important for socialists in the union to argue that these defeats aren’t inevitable—that workers can fight back, and that their union should be rallying them to do so.

On his campaign website, Allinson wrote, “It is essential that this election does not become a battle between Len McCluskey, offering more of the same, and Gerard Coyne, offering to turn the clock back to the bad old days when our union backed New Labour even while they attacked our own members—and saw membership decline.”

Many will want to ensure a Corbyn supporter isn’t driven out of leading Britain’s biggest union. But those who want to promote Corbyn’s politics would do better to look to Allinson.

McCluskey’s support for Corbyn is unreliable. He pressured him not to appoint left winger John McDonnell as shadow chancellor—and to support renewing Trident nuclear weapons.

And in a recent interview he raised the possibility of Corbyn having to resign before 2020 to reverse Labour’s dire decline in the polls.

McCluskey has to his credit put Unite’s support behind anti-racist initiatives and backed anti-racist demonstrations. But his response to a race to the right on immigration has been to make dangerous concessions.

And as the scapegoating of immigrants poisons British politics and society, we need unions to stand firm against it. Workers can only win when they stand united.

The SWP remains committed to working alongside McCluskey and others in the union leadership. But we believe it is important to put forward a real alternative and win workers to supporting it.

Unfortunately the election’s arbitrary timing makes this difficult. Candidates have only a one-month window to get nominations from 50 branches. Without the resources, connections and media support that McCluskey and Coyne enjoy, it will take a real push to get Allinson on the ballot paper.

So it is urgent that Unite activists waste no time in getting their branches to arrange nomination meetings and put forward a grassroots socialist candidate.