Nick Clegg, up in Glasgow for his party's conference, refused to tell the BBC's Andrew Marr yesterday what "red lines" he would draw in any negotiations for coalitions in the future.
That's not surprising. First, Mr Clegg doesn't yet know what potentially awkward and embarrassing policies his party activists might choose to commit themselves to. They may, for example, decide to make the reintroduction of the 50% tax rate party policy in today's debate on the economy, in cheerful defiance of the Coalition agreement.
Or there may be a resurgence of interest in Vince Cable's exciting "mansion tax" (under which semi-detached 1930s houses in not-very-fashionable London postcodes count as mansions), an idea he's been quieter about since the rise in house prices seems to be so popular with voters, but which hasn't been forgotten.
Then there are noises about lifting everyone on the minimum wage out of tax altogether - a potentially popular, and perhaps even sensible, aim - but, since it would add well over £1000 to the personal allowance, a fairly expensive commitment.
Besides which, Mr Clegg has the difficulty of not knowing whether there will be any negotiations over a coalition, let alone with, or by, whom. Yesterday, he said that there had never been the remotest possibility of a Labour/LibDem coalition the last time because "the numbers didn't add up", which rather makes you wonder why his party negotiators spent all that time talking to them.
But another General Election at which no party has an overall majority, or one which is workable, is quite plausible. Ed Miliband is almost as unpopular as Mr Clegg, and both his standing and his party's relatively slim lead make it, on the face of it, likely that Labour won't manage an overall majority (though the party's lead in Tory/Labour marginals is healthier).
Without a change of leader, however - maybe even with one - it would look bizarre for the LibDems to perform a volte-face. That's why, despite the attempts of the past week to distance their policies from those of the Tories, and set out a distinct agenda, the subtext of Mr Clegg's replies was clear. A Labour win, he said, would "wreck" the recovery; but the recovery the Tories would bring about would only risk being "unfair".
A third reason for Mr Clegg to be cagey is that most party activists are social democrats well to the left-of-centre, while he is a liberal. But in this, oddly enough, he is more in tune with LibDem voters than colleagues around him at conference. Activists would prefer an alliance with Labour, but three-quarters of voters who say they still support the party would rather have a continuation of the current coalition - which must surely also be the case for most of the undecided voters the LibDems have any chance of winning over, since they would otherwise presumably vote Labour.
From that point of view, the huge loss of LibDem support - down from almost one-third of voters after the first televised leaders' debate in 2010 to 9%; and reflected in Scotland by the two-thirds cut in the number of MSPs in last year's election - may not be the most important factor.
Mr Clegg must always have suspected that voters who supported his party solely as a protest against the last Government's stance on Iraq would return to Labour under a new leadership, and have calculated that he could confirm that suspicion at once by going into government with the Conservatives.
Far and away the LibDems' biggest difficulty, however, and the most compelling reason for Mr Clegg to be reluctant to offer any hostages to fortune, is the party's broken promise on tuition fees. Having had a taste of pop stardom with the catchy auto-tuned song of his apology ("I'm sorry, I'm sorry, I'm so, so sorry/There's no easy way to say I'm sorry"), Mr Clegg has no doubt clocked the title of this summer's big hit, Blurred Lines, and prefers it to "red lines".
The really appalling aspect of this broken pledge was not just that it was broken, but that it was actively horse-traded. Since it was a central, and possibly the most successful, policy in terms of recruiting voters, you might have thought that Mr Clegg would make it one of the conditions of the Coalition agreement.
But instead the LibDems prioritised a referendum on a change to the voting system which not even they supported, and reform of the House of Lords (which every party supported) but which they nonetheless managed to turn into a dog's breakfast.
A quick glance at the full agenda for this week shows that issues such as these, of little if any interest to most voters, are still the mania of Liberal Democrat activists. Yesterday it was zero-carbon Britain and cycling reform, today it's cohabitation rights and the Diversity Engagement Group's campaign for gender balance. It's not that these are of no interest, but they suggest that conference attendees care more about the obsessions of policy wonks and the Westminster bubble than things that matter to ordinary voters. The tuition fees fiasco was a damning and damaging demonstration of that.
What can Mr Clegg say for himself? Well, he can offer more than just his triumph over the tax on plastic bags, a topic which voters seldom fail to list in their top three priorities. It turns out, in any case, that this is not a LibDem but a Coalition policy, and is already in existing legislation, but hasn't been implemented.
There are still reasons to think the LibDems may yet have a chance of recovery, or at least of doing less badly at the next election than the polls suggest. There is, first, their perpetual advantage, which is simply that they are neither the Tories nor Labour (or, for Unionists in Scotland, the SNP). For a lot of undecided voters, the LibDems are still a default option. And the relative closeness and unpopularity of all parties makes that a defensible position.
But their main boast is simply that they have stuck the course; the party has shown that coalition is not bound to collapse, and that compromise is possible. And if, in some areas, they have been merely petulant or obstructive, and in others chosen idiotic priorities, they can nonetheless claim real victories in modifying Conservative plans. The rise in personal allowance is, in my view, far and away the best of these, but LibDems can also point to concessions on education, welfare reform and civil liberties. Despite everything, I wouldn't bet against Nick Clegg still being Deputy Prime Minister in 2016.
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