I think that in general people are far to harsh about Clegg, had he managed to construct a coalition with Labour rather than the Tories, I really do doubt that he would be in this position now.
I think he was very naive, not a good thing in a politician, I think he got trussed up like a kipper by the Tories.
He allowed them to take far too much out of the Libdem manifesto without getting very much in return, the Tories are delighted to have a whipping boy to take all the flack for their particularly nasty,pernicious policies.
He has often said that he didn't win the election and that he is the junior partner and as such cannot implement all his policies, he clings to the tax thresholds raise, which he gets no credit for, because people are so pissed off about tuition fees.No one thinks about his pupil premium either.restoring the link between earnings and pensions goes unnoticed.
so from a very naive start where he left himself very little to work with, he has failed to promote what achievements has had.
Doubt he'll go before the election, but he will have to shortly after.