Following Nick Clegg’s success in the first Leaders’ Debates last Thursday, there has been a dramatic shift in the national opinion polls. The sheer scale of the increase in Lib Dem support has taken everyone by surprise and has changed the whole tone of the election campaign. To put things in perspective the Poll of Polls started last week with the Tories on 39%, Labour on 30% and the Lib Dems on 19%. We have yet to see a full slate of polls carried out since the Debate, but tonight’s YouGov poll (not normally the best for the Lib Dems) puts the Lib Dems on 33%, the Tories on 32% and Labour on 26%.

This is a complete sea change. What seems to be happening, at a national level, is that as people now see the Lib Dems on similar levels of support to the other parties, those that viewed a Lib Dem vote as wasted are now reconsidering that view. So instead of it being a blip in support, it is becoming a virtuous circle. Indeed if Labour continues to run in third place for a few more days, it may be them that start to suffer the tactical squeeze. This certainly poses a real dilemma for Labour. If they start to attack the Lib Dems hard now, its all going to look very odd in comparison with Gordon Brown’s “I agree with Nick” line in the debate.

The last week has shown everyone how unpredictable politics can be, and how volatile the mood of the electorate is. The Lib Dem line, put over so well by Nick Clegg, that we are the best way of giving the country real change, wheras a vote for Labour or Conservative is a vote for more of the same, has been the trigger for a dramatic shift in support – so dramatic that the whole outcome of the election is now up for grabs. The final 18 days of the campaign will be very interesting.