Some time within the next thousand days, Britain will vote as to whether or not it wants to remain within the European Union. It will be - without doubt - one of our nation's most momentous and most uncertain decision.
The choice is stark: Partnership or isolationism? Internationalism or tribalism? The ability to be at the centre of global events or a retreat into petty insignificance?
The case to remain in the EU should be self-evident. As my colleague, Tim Farron MP, wrote recently in the Fresh Start magazine:
"A generation ago there were nuclear weapons on the soil of some of our EU partners pointed at Britain. Now we are sitting round a table together. Were that the only case for staying in the EU it would be pretty overwhelming."
And yet, despite everything the outcome is far from certain.
David Cameron's decision to hold the referendum was essentially a short term tactical device intended to prevent the two halves of an irreconcilably divided Tory Party from killing each other in the run up to the 2015 election. Now, however, he has won that election he is forced to make good on his promise, and there is no guarantee for him that the referendum will heal his party.
While I have no doubt that the PM will try to present any outcome of his negotiations to reform the EU as grounds to retain membership, it is inevitable the Prime Ministers will focus his message on his struggle to hold his own party together. So, just when the UK most needs strong leadership, David Cameron will be talking inwards not outwards, and fighting the wrong battle.
Meanwhile, the Labour Party is engaged in an extended piece of naval-gazing. While not doubting that our own party was devastated by the outcome of the election, it is the Labour party which seems most traumatised. Judging from their own leadership election, with such a range of policies and ideas it is hard to envisage the party quickly 'moving on', once their leader has been chosen. A strong and speedy defence of the EU from Labour looks unlikely given the work they must do to patch up their internal divisions.
In contrast, the Liberal Democrats have two outstanding candidates in their own forthcoming leadership election. What's more, whichever candidate emerges successful will have the huge benefit of leading the only party united in its determination to remain in the EU. As such they, and they alone, will have the only solid platform from which to make the case for EU membership.
In such circumstances, I find myself genuinely excited at the prospect that Tim Farron will be the leading voice in that campaign. I have only respect for Norman Lamb, but when it comes to communicating with passion and inspiration Tim has few, if any, rivals in British politics, and that is just what will be needed for this referendum fight.
What's more I know Tim has a very special ability to connect with people in the gut: and, for the case for EU membership to be won, the YES campaign will need to make an emotional not just a managerial appeal to voters.
I have no doubt that those organisations with even a passing understanding of global economics will make a persuasive economic case for membership to their own constituencies: the jobs which will be protected and created, the markets which will be kept open, the investment opportunities and so on: the numbers and statistics will be wheeled out for public consideration in the coming months. But I believe that the decision will be made by what people 'feel' about the EU as much as what they know.
It is this that could make the EU Referendum the defining issue for the new Liberal Democrat leader and indeed the issue on which the party begins to mount the path back. And given the nature of this opportunity and the challenge of touching people emotionally I have no doubt with Tim Farron as the leader the Lib Dems will play a pivotal role in ensuring the UK has a great future as a full and active member of the European Union.Suggest a correction