On the other hand, abandoning PR while giving Nick Clegg a cabinet seat (probably Foreign Office) and perhaps Cable as Chancellor is a much better strategy for the Tories. Not least because it gives Cameron an excuse to ditch his old friend/liability Osborne. This strategy locks the Lib Dems into the Tory project, and drains their credibility, while the Tories strengthen their electoral position (by faffing about with a commons committee and gerrymandering the electoral boundaries). Once they feel they have fixed things up enough, the Tories can ditch the Lib Dems. I think this would take more than six months, and probably ends with Clegg crossing over to the Tories.
It is in Labour's long term interest to stand back and let this happen.