Chancellor George Osborne has said the Newark by-election win was a "strong win for the Conservatives" and it was "disastrous" for the Labour Party.
Asked what he thought of the Ukip performance after the anti-EU party came second, he said:
"The Ukip vote was down on where it was a few weeks ago. We have an argument we can take to the country now about the change Britain needs."
More top news
It'll become increasing cloudy tonight, with outbreaks of rain in the northwest
Six months on from the referendum, Political Editor Robert Peston takes a road trip to find out what people feel about Brexit now.
Donald Trump has been criticised for appointing a man who once sued the Environmental Protection Agency to be its new boss.