The problem is that parties "campaign in poetry" but "govern in prose".
So as Mr Tprisas found out, you can promise anything in opposition but when you expect someone else to pay for it, that's when reality bites.
Listening to the odds and sods of the looney left, all our financial problems would be solved by taxing the "rich". In their case, the "rich" is anyone earning (and I stress earning) more than they are. Whilst I might have some sympathy for taxing the so called tax exiles (Denis O'Brien etc), even that is a bit clichéd , since in many cases their assets (and incomes) are located overseas (so easy to say but very hard to do).
There is a political risk that the next Govt may have to rely on a "collective" of independents (most of whom seemingly cannot agree what day of the week it is).