Tories:

“This is a regrettable and frankly counterproductive decision. As  Douglas Carswell said, the only way to get a referendum on the EU is to return a majority Conservative government. The Conservative party will contest the forthcoming by-election vigorously to make sure the people in Clacton have a strong conservative voice in this parliament and the next.”

‘The Conservative Party will contest the by-election vigorously, to ensure that the people of Clacton have a strong Conservative voice in this Parliament and the next.’

Labour:

“Douglas Carswell’s defection is a hammer blow to David Cameron. Confidence in David Cameron is collapsing inside a Conservative party which is divided and running scared of UKIP. David Cameron’s weak leadership has seen him abandon the centre ground, repeatedly trying to pander to his own right-wing backbenchers rather than concentrate on the needs of the country. Now even his own side are abandoning him.”

Panic stations.