For Nigel Farage, the Telegraph notes, the stakes this evening could not be much higher:

Addressing a rally in Broadstairs, Kent, Mr Farage said Thursday was “the biggest day in my political career”, with polls suggesting he faces a tight battle to win a Westminster seat.
Mr Farage cast his vote in his Kent constituency of Thanet South knowing that his political future is on the line, having promised to step down as party leader if he is not elected.

Arguendo, suppose that Farage loses, and that he has to step down. Then what? Well, in my view, then . . . disaster. Disaster for the anti-EU cause; disaster for the virtuous momentum that Farage and his friends have created; disaster for the positive narrative that he has so assiduously helped to build. Disaster, ultimately, for common sense.

Over the past decade or so, Nigel Farage has done an absolutely fantastic job of bringing the European issue to the attention of the public, and of prevailing upon the Conservative party to take it seriously. Furthermore, the man’s visible position within the European parliament has given him the chance to play the freedom fighter behind enemy lines. By standing for election to Westminster, however — and by pretending that his party is anything more than a single-issue outfit — he has potentially jeopardized that progress and damaged his name. As of this moment, it seems unlikely that UKIP is going to end the night with more than two seats. Indeed, it is possible that they may end it with just one. If this happens — especially if Farage himself loses his bid — the papers will be full of “Farage Falls” stories, and his enemies will make it seem as if his EU project and his parliamentary ambitions are one the same. That, I’m afraid, will be extremely damaging to the cause.

In truth, the argument against British membership of the European Union and the personal fortunes of Nigel Farage are entirely discrete. But that they are being treated as if they were inextricably linked is Farage’s own fault. As my friend Roger Humber wrote last year, by focusing on other policies and by attempting to give UKIP a more considerable presence within parliament, Farage has effectively diluted his power. Humber wrote that Farage was:

turning UKIP into a ragbag of Poujadist resentment, claiming to have “policies” on the National Health Service, wind farms, housing, welfare, the Treasury, and a range of other issues, which lack any coherence and simply attract the “anyone but them” vote, much as the Scottish National Party did in the Scottish referendum. Getting members into Parliament is a necessity in order to influence and scare other parties; UKIP’s platform should concentrate on Europe alone. Insofar as the EU figures in Farage’s policies at all, border controls and immigration are the issue, but even this connection is vague, and the current government seems to be blamed as much as are EU requirements for our immigration problems.

Really, Humber submitted back in October, Farage had two options. He could either become “one of a dozen UKIP MPs for the duration of one Parliament, more concerned with Punch and Judy politics than with giving the nation the leadership no one else on the political scene is able to provide”; or he could stick to his project and “become the greatest British statesman since Churchill.” Alas, he seems to have chosen the former path. Superficially, at least, it is understandable why he did so. Late last year, the prospect of a sizeable UKIP showing looked fair. Today, however, it does not seem likely at all. In fact, it is now possible that UKIP will do worse in 2015 than it did in 2010. The tide, you might say, has turned.

And that, of course, is rather the point. By wading into ordinary domestic politics, Farage has served himself up as a hostage to fortune. He has set himself — and the movement of which he is a totem — up for failure. He has pushed his party and its representatives onto terrain on which it is reflexively uncomfortable, thereby alienating some of his allies and diminishing his brand. And he has run the risk of alienating single-issue voters by making it appear as if opposition to the European Union is an inherently conservative position to take. If he loses this evening, it will not just be his career that will be over, but a whole era of modern British politics. For that reason, I hope that it does not happen. But, if it does, he will have nobody to blame but himself.