Here's what happens when you wargame four different kinds of Lib Dem coups. None of them are very pretty.
Keep Clegg – keep the coalition
The rationale: The Liberal Democrats are a party who finish what they've started. They're four years through a five-year government they committed to and their leader is the man to complete his task. The time for revision is after a general election, not before it.
Best-case scenario: The public reward the Lib Dems for financial austerity and saving the recovering economy. In 2015 the party saves enough seats to enable it to maintain the balance of power in the next parliament, achieving Clegg's mission of staying in government.
Worst-case scenario: The public turn against the man who broke his promise on tuition fees and the party which allowed the Tories to slash Britain's public services. Dozens of Liberal Democrat MPs lose their seats, leaving a rump of ten or so left. This kind of wipeout seems a lot more plausible now than it did before this year's European elections, when the number of Lib Dem MEPs was slashed from 11 to just one.
How likely is it? Sticking with the status quo is the most likely option, for the simple reason that actually achieving change is horribly difficult and damagingly painful. That doesn't make it the most sensible option, though.
Keep Clegg – ditch the coalition
The rationale: Nick Clegg could decide to establish a confidence-and-supply arrangement with the Conservatives, allowing David Cameron to govern as a minority for the remaining months until the next general election without Lib Dems in power. Doing so would help voters realise there's more to the Lib Dems than just being Tory lackeys in the run-up to next year's vote.
Best-case scenario: Crunch seats like Cambridge, where hostility to the coalition could be decisive in costing Liberal Democrats their seats, are brought back into play.
Worst-case scenario: Those same wavering supporters decide this is yet more evidence of Lib Dem inconsistency – and go ahead and punish the party anyway.
How likely is it? It seems pretty improbable, because Clegg is so closely allied to the coalition project. But as he began to make clear in his conference speech last year, there is more to this man than just being Cameron's best pal. He is ambivalent about who he shares power with; so perhaps the lure of five more years might persuade him to give up influence for 12 months or so.
Ditch Clegg – ditch the coalition
The rationale: The Lib Dems decide to make a clean break with the past. They walk away from power and the man who led them into this mess. Instead they reassert their values and identity, and prepare a clear set of red lines for coalition negotiations – with the Labour party, of course.
Best-case scenario: The boldness of such a move raises eyebrows across Westminster – and the country. The public interpret it as a temper tantrum – but respect the Lib Dems for rediscovering their principles and reward them for ditching the man who led them astray.
Worst-case scenario: Lib Dem flakiness becomes inextricably linked with their brand. Future coalition talks are derailed because the other parties realise they can't be relied on to stick it out for five years. The exiled, ousted Clegg tells his party of stabbers: 'I told you so.'
How likely is it? Yet again, the credibility question makes this option seem so unpalatable as to be unthinkable. The Lib Dems, ultimately, have created a trap of their own making. They have to accept that they are in government for five years, whether they like it or not.
Ditch Clegg - keep the coalition
The rationale: It's the leader, not the strategy, which is the problem. Clegg is 'damaged goods' like no other party leader. He is personally despised by many taken in by the 'Cleggmania' of 2010 who have felt betrayed by his policies in power. While getting rid of the coalition might be untenable – it's too late to ask voters to forget about it – changing the person in charge of the party could make a real difference.
Best-case scenario: Today's polling from ICM shows just what would happen: unwinnable seats become contestable once more. Defences that seemed impossible are at least worth bothering with. MPs preparing to lose their jobs decide they actually stand a chance of sticking around, after all.
Worst-case scenario: Clegg's departure destabilises the government, derailing the economic recovery. The Tories waste no time in pointing the finger at the Lib Dems. And angry voters respond accordingly.
How likely is it? Clegg has made clear he's not going anywhere. And the truth is that senior colleagues don't seem to have the cojones to attempt to oust him. Perhaps if he were willing to slink away by himself, it might become plausible. But with Clegg in robust mode – he must have thicker skin than anyone else in British politics – it'll be a real shock if this scenario comes to pass.