"which might – just might – result in the Lib Dems saying ‘sod you lot; Ed – do you fancy a go?" There is zero chance of that ever happening. Much, much more likely, if the Lib Dems get fed up enough with the coalition, is a minority Tory government. There is nothing in it for Labour, they only need to look at history, Callahan and Major had enough problems with their own minority administrations, and those were not even coalitions, and Cameron is barely keeping his party together, why would Miliband want to join a coalition that did not even have a majority, when as things stand, he could win the next election with a majority? He would be a PM for barely 2 years at the fag end of a parliament, and would probably lose the next election badly (indeed, a Lib/Lab coalition would benefit the Lib Dems more than Labour the way things currently stand). Better (in purely electoral terms) for Miliband to continue to watch the Tories implode (and let's be honest, Lib Dem unity has been a revelation during this parliament!). So Miliband will politely rebuff any lib Dem overtures for coalition. Then there is a bigger chance, but still slim, of an early election. That would require a vote of no confidence in the government, even with the Lib Dems moving into opposition, and leaving a Tory minority, there is little to appeal to the Lib Dems in an early election, so they will support confidence and supply motions to any Cameron minority government. The only other possibility of an early election would be if both Labour and the Tories supported an early dissolution, meeting the 67% requirement. I can't see any circumstance where both Labour and the Tories would want to go for an election simultaneously. Currently I think Labour would want one, but not the Tories, as Labour would win, if we believe the polls. So I personally think this thesis is based on a pretty flawed analysis of the current state of affairs.
Imagine you’re a slightly excitable aide to Ed Miliband and plotting how he can be Prime Minister by Christmas, with you getting a new nice job in 10 Downing Street as a result. What would your plan be?
Knowing that we now have fixed-term Parliaments, what you would want to plot is a falling out between the Conservatives and the Liberal Democrats, which might – just might – result in the Lib Dems saying ‘sod you lot; Ed – do you fancy a go?’.
How might you go about trying to pull off this unlikely occurrence?
Well, first you want to pick an issue that many Liberal Democrat activists feel really strongly about, such as political reform.
Then you would want to find something which was promised in the Coalition Agreement – to double the Lib Dem angst.
Next you would hope and pray for (and perhaps give a few subtle nudges to encourage) Conservative MPs to vote in large numbers against your selected issue, leading to lots of Liberal Democrat unhappiness.
To really add to the Lib Dem angst, you’d even been hoping for them not only to break the deal but then act with outrage when anyone suggests to them there might be any consequences of them breaking the coalition deal. Perhaps a few hotheads from the Tories will really help out by labelling the suggestion that there might be consequences if they break a deal as ‘blackmail’. Nothing like a little touch of arrogant assumption that you can break a deal with impunity to really annoy Liberal Democrats, you may well think.
Then you’d quietly slip up to a few Lib Dems and say, “Look, we know hung Parliaments are tough and – frankly – doing a deal with Labour wouldn’t have been a bed of roses for you either. But just look at those Tories: large numbers of them have broken the deal and think they should be able to do so without any comeback. Do you really think things are going to work out in future? However, Ed’s willing to offer you this rather nice alternative…”
Unlikely? For sure.
But what’s weird about it is the enthusiasm of so many Conservative MPs to follow the script. It’s a strange, strange strategy to take.
UPDATE: Nick Thornsby makes some good related points over on Lib Dem Voice.