If there is one message Labour and Conservative politicians should take into the next election it is never to underestimate the Liberal Democrats. They always do better than you expect them to, especially in an electoral system where there is no rational reason to vote for them.
There have now been two opinion polls this month putting them at 22 per cent, the level they reached at the last general election and a high-water mark in recent times. Could it be that the Liberal Democrats under Clegg and Cable can make a pitch to overtake Labour and become the real opposition to the resurgent Tories?
Martin Kettle certainly thinks so in today's Guardian. He makes an interesting case. Vince Cable is having a good crisis, Kettle argues and likens the present crisis to the first world war, which led to the death of the old Liberal party and the second world war, which was the making of the modern Labour Party. Some of this is wishful thinking: the Guardian is full of journalists who wanted the Social Democrats to "break the mould" in the 1980s.
Clegg and the Lib Dems could yet be squeezed. But don't rule them out just yet.