A lot of people have now got used to the idea that Labour have an electoral advantage and can come behind the Tories in votes but still do well in seats because of the way Labour can win urban seats with less votes than the Tories get in rural seats. This has nothing to do with the size of the constituencies as the Tories would argue but everything to do with luck and what is called differential turnout - Less people vote in poorer urban areas, so you don't need as many votes.
But the guy who predicted the Obama win to a remarkable level of accuracy has said that Labour are destined to do far worse than the universal swing idea suggests. The Tories are doing much better in the seats they need to win. For this reason 35-36% might just be enough to win them a majority. The rise of the Lib Dems may well have helped them in this task even if the Lib Dems defend all their seats and gain a few from the Tories.
This election is wide open - if the Tories get around 33% then yes, we will have a hung parliament, but if that rises to 35,36,37% then the Tories might just nick a small majority.
It is the gap between Tory and Labour that will make the difference. Labour down on 26 or 27% could be 9 or 10 points behind. For the Tories that would be enough. For this election, all progressives are going to have to hold their breath!