"Expecting a government to define what it's going to do for 5 years in adcanced is criminally stupid."
I also agree....but with a caveat.
Taking the "...few big ticket ideas." ideas, and for ideas, read promises, in TTT's post, I am of the view there must be compelling, meaningful reasons why they are not delivered on.
If a big promise induces the nation to return the party who made the promise is not delivered, then I think there's an argument to suggest the loss of the mandate.
If you are induced into a contract, and the promise the contract made in order to induce you is not delivered, it is a breach of contract.