As I’ve written in The Independent, last week’s election results still leave me feeling numb. The Liberal Democrats are not a political machine but a human family, made up of dear friends and colleagues, striving together in a common cause. Which is why the loss of so many excellent MPs, councillors and staff is not just a political catastrophe but also a personal heartbreak.

Liberalism and liberal values are under threat from a triumphalist Tory party in hock to its right wing and from the forces of nationalism and isolationism. No one can rely on a Labour ‘opposition’ who have never got it on civil liberties, immigration, Iraq or a new politics. Liberal Democrats need to pick ourselves up and lead the fight.

This will be a tough challenge, but liberals have done it before. We came back from near oblivion in the 1950s and ‘60s to challenge the Tory–Labour stranglehold on power, building on our local roots, fighting alongside local campaigners to make life better in a myriad of little ways for individuals and their communities. As an activist and councillor and MP I’ve been part of that endeavour all my political life.

I don’t doubt our resilience for a second. Underneath the shock from last week’s results is something powerful and determined. And the more than 11,000 members who have joined the party since election night give us reason for hope.

But if we are to rebuild, we have to learn the lessons from 7 May. We need to understand why we failed to communicate both our genuine achievements in coalition and our hopes for the future. We need to look at our election campaign and consider where it worked and where it didn’t – and how we campaign from now on with such a tiny parliamentary party. We need to be clear what is the point of the liberal Democrats in a tougher, more complicated political world.

These are processes which of course need to involve the entire party, and will stretch well beyond the leadership campaign. The Autumn Conference will be a key opportunity to debate these issues. But the leadership contest gives people a chance to discuss and think about them over the next two months.

Above all, now we have a chance to make a fresh start – to elect someone who can embody liberal values, someone to make the positive case for civil liberties, a more equal society, a green economy, an open and internationalist approach and the political reform that this country needs to avoid it splitting apart – someone who can stand up for a freer, fairer, greener Britain.

We need someone with the vigour to campaign up and down the country, day in, day out, who can rebuild the party from the bottom up, using all the tools of modern campaigning but remembering that what people want is for politicians to talk to and listen to them and to be true to their word.

Since last Thursday, I have been humbled by all the messages urging me to stand for the leadership – so today, I put myself forward to be the next leader of the liberal Democrats.

My aim is for a campaign which will be positive, optimistic and unifying. I am unshakeable in my belief that Britain needs liberal values and a liberal voice. With your help and support, I can be that liberal voice. I hope you will join me.

* Tim Farron is Liberal Democrat Spokesperson on Refugees and MP for Westmorland and Lonsdale.