A short-lived rainbow coalition to deliver electoral reform?

As has been widely reported, the combined forces of Labour and the Lib Dems are insufficient to command a majority in the Commons. Any Lib-Lab coalition would need to include a range of smaller parties as well, and it is hard to imagine such a diverse group holding together through the difficult times ahead.

However, I wonder if they could hold together long enough to push through electoral reform, and immediately call another election. Certainly the idea must appeal to Clegg.