Ukip has benefitted from "a very tough and difficult recession" and engaged voters because of their "popular policies and great rhetoric", David Cameron told Good Morning Britain.
The Prime Minister urged voters not to be swayed by Nigel Farage's anti-EU party and instead stick with the Conservatives who stand for the "politics of the answer".
"When you have had a difficult recession, when you have problems like a welfare system that needs reform and problems with the European Union it is quite easy for someone to come along with some popular messages and some great rhetoric."
More top news
People walk slower while texting on their mobile phones to try and avoid accidents, according to new research.
The large piece of debris washed ashore on Reunion Island could be be from the missing Malaysian airliner MH370, according to a US official.