A victory for Jeremy Corbyn in the coming leadership election is crucial for the future of the British left, writes Lindsey German

So today Angela Eagle challenges Jeremy Corbyn for Labour leader, and we have another summer of campaigning. This time it’s even more important because the ruling class and its allies in Labour will throw everything at this contest to defeat Jeremy. We have seen in the past few days the lengths to which the Blairites and many others in the PLP will go to defend their own interests and to defeat any left wing ideas within the party. They have deliberately done everything they could to damage Jeremy, which has meant giving succour to a discredited and dishonourable Tory prime minister.

But they have not succeeded – so far. It is obvious that plan A was not to have an election at all but to exert concerted parliamentary and media pressure to force a resignation.

The plan amounted to institutionalised bullying of a man repeatedly referred to as having decency and integrity – qualities which count for little apparently in the PLP. It is shameful that so many MPs were dragged into this, no doubt hoping that the coup would be quickly over and that they could all get back to business as usual.

It is to the enormous credit of the trade union leaderships that most have signed a statement supporting Jeremy. No doubt this in part reflects an understanding of Jeremy’s popularity among trade union activists, but it also shows that his policies have a real resonance among the wider left.

All credit too to the young people around Momentum who have campaigned so hard over this and who are determined to see him re-elected. Labour MPs now face challenges as to whether they will be democratically accountable to their members – as they should do.

The struggle now enters a new phase with an election campaign for Labour leader. The left has everything to play for. Whichever way people voted in the referendum, it is now about building a serious left both in and outside the Labour Party, about fighting against attempts by both main parties to further restrict immigration, about challenging the appalling austerity which has greatly increased inequality and savaged funding for public services, about challenging the threat of racism and the far right.

In the next week alone we have the Chilcot report into the Iraq war, the strike by teachers and some university lecturers, the ongoing Southern trains dispute, and the Durham miners’ gala. All of these areopportunities to get our message across. There are also already dozens of demos, rallies and meetings in defence of Jeremy, and these need to take place up and down the country.

We know where Jeremy Corbyn stands. We can probably guess where Angela Eagle – a woman who voted for the Iraq war and appears not to have the support of her own constituency members – does. So this isn’t about one man, important though he is. It is about the future of the left in Britain and more widely, because a victory for Jeremy is a victory for us all.