That well respected constitutional authority The Sun newspaper has decided that Gordon Brown is doing something terribly dastardly by not immediately clearing out of No.10.
Quite apart from the fact that constitutionally, in the absence of an immediate Lib-Con pact it would be unjustifiable - and politically irresponsible - for him to resign, there are also democratic grounds for him staying; even for another five years. Not that I'm advocating that, but - here is the reasoning.
The Conservatives have 306 seats, Labour 258, and the Lib Dems 57. The Conservatives got 37% of the vote, Labour 30%, the Lib Dems 23%. So, no party has a majority of seats or votes, but a LibDem coalition with the Cons would have both (only the former matters constitutionally, but the latter would be happy for democratic legitimacy) and a Lab-Lib coalition would have the latter, and could reach the former without too much trouble. A Lab-Con pact is pretty implausible.
So the question is, why should a Lib-Con deal be preferable to a Lib-Lab one? The first would be that it is over-sized, which would be good from the representative democracy perspective, since more voters would have some voice in government. But power spread more broadly is power spread more thinly, so that is not necessarily an advantage. Moreover, over-sized coalitions are more likely to contain destabilizing internal tensions. The second reason is that the Conservatives are the biggest party. On a majoritarian understanding of democracy, this gives some legitimacy to govern, and indeed our democracy usually confirms this by giving the biggest party an artificial parliamentary majority to govern with.
But there is also a case for a Lab-LibD coalition. First, it is close enough to a majority to have a plausible chance of governing, especially if it reaches agreements with left-leaning nationalist parties. Second, Labour and Lib Dems are close enough programmatically to reach agreement on a number of issues quite easily. It would be, in my view, a more cohesive coalition than a Lib-Con one. On Europe, immigration, public spending, bank regulation, sexual and ethnic diversity, territorial issues and, crucially, constitutional and electoral reform, the two parties are barely distinguishable. On these same issues, the Lib Dems and the Conservatives are clearly quite distant.
So, a Lab-LibD coalition would probably be more stable than a Lab-Con one. A Con-Lib coalition can only work if the Lib positions are largely ignored by the government on most issues. At which point, rather than a coalition in which a broad range of opinion is represented, it simply becomes a Lib Dem favour to the Conservative party.
Having said all that, Labour could do with a new leader and a spell in opposition, and the media pressure for the Conservatives to govern is irresistible. It would probably destroy the Labour and Lib Dem parties if they deny the Tories their right at another turn exercising absolute power. But that doesn't mean that it's overwhelmingly the only democratically legitimate outcome.