A leaders' debate is out of the question

I agree with Nick Clegg that he has done well to trap Nigel Farage into signing up for a face-off

In the ledger of tiny gains and losses by which party morale is measured, it is a point for Clegg

There is life in the parrot yet. Nick Clegg has challenged Nigel Farage to a debate on Europe. The yellow bird of liberty twitched and looked quite perky for a moment. The Ukip leader was taken by surprise and hesitated for 24 hours. His first response was something muffled about wanting David Cameron and Ed Miliband to take part too. It was not until Friday that Farage agreed to take part, with or without the others. By then, the damage was done. Plain-man Nigel was revealed as fake, an indecisive, odds-calculating politician.

This moment of cowardice will be forgotten by the time the debate takes place, if it ever does, but in the ledger of tiny gains and losses by which party morale is measured, it is a point for Clegg. What is more, backing our membership of the European Union unconditionally gives the Lib Dems definition. The last time YouGov asked the straight in-out referendum question, earlier this month, 36 per cent said they would vote to stay in, 39 per cent to leave. Clegg can see that 36 per cent is larger than 10 per cent, which is the average Lib Dem share of the vote in opinion polls.

The Lib Dems are starting to respond to their adversity with a bit of fight – not least because they have so little to lose. The party's website was revamped last week. It now has an error message with a picture of Ed Balls that says: "Just like Labour's plan for the economy, this page doesn't exist." Childish and silly perhaps, but it attracted some attention on the internet.

Hence the challenge to Farage. Clegg understands the politics of leader debates, having been the beneficiary of the first leaders' panel-show in the last election campaign. Just as he knows that 36 is larger than 10, he knows that 10 is smaller than 12, which is the average percentage scored by Ukip in the polls. He knows, too, that it is usually in the interest of the underdog to challenge the overdog to a debate. Just as Alex Salmond knows it is in his interest to challenge Cameron to a debate on Scottish independence, and just as Cameron knows it is in his to refuse. Farage might be only the third dog, but it is still worth the fourth dog having a go at him.

All good clean fun, and I agree with Nick that he has done well to trap Nigel into signing up for a face-off before the European Parliament elections in May. There are details to be decided – really, it ought to be on television rather than radio – but the larger significance of Clegg's little victory is that it helps to illustrate why the leaders' debates are unlikely to happen in the general election campaign next year.

The debates happened last time only for two reasons. One was that Cameron agreed to them when he was still the underdog. In the early days of Gordon Brown's time as Prime Minister, the Conservatives had to harass and destabilise – anything to scare Brown off a snap election in which they felt he had the advantage. The other was that, once Brown had messed that up and the balance of advantage changed, Cameron's inexperience and over-confidence meant that he failed to pull the plug.

Thus he went into the debates as the frontrunner, against two different kinds of underdog: the battle-scarred, war-hardened leader who got us through the crash, and the fresh-faced Blair-alike new boy. No wonder they didn't go well for him.

Cameron will not make the same mistake again. He may be behind in the polls but as the incumbent he has most to lose. Hence the official line. "We're up for them," says a spokesman for the PM. "We'll do them." These are sentences in which the "not" is silent. There are provisos and conditions attached to the display of official enthusiasm. One is that the PM refuses to consider the same format as last time, of three debates with three leaders over 15 days. That meant that the campaign consisted of "the build-up to a debate, a debate, and the post-debate analysis, times three, and then the election", says a Tory source close to the negotiations with the broadcasters. "That was crazy. We're not doing it."

Naturally, that is precisely the format the broadcasters have proposed. They know that to suggest variations from last time – such as to include Farage in one debate, or to exclude Clegg, or to stage fewer debates – makes agreement harder. Loose ends give a reluctant party the chance to obstruct talks without looking as if they are doing so. Tony Blair always said he was willing to take part in debates, but his negotiating team pretended to be reluctantly unable to agree terms.

This time, the broadcasters think that they have precedent on their side: the debates happened last time, so let us do them again. It won't work like that. The Prime Minister refuses even to open talks about the debates until October. Some excuse about "trying to run the country at the moment".

I was divided about the televised debates last time. They meant that the campaign was dominated even more by the party leaders, but they also attracted huge audiences for long and serious discussions.

But the democratic merits are irrelevant. They are not going to happen in next year's campaign.

twitter.com/@JohnRentoul