UKIP leader Nigel Farage claimed a "sea change" in British politics as they gained more than 140 council seats in the local elections.
There is no question that the day belongs to UKIP and Nigel Farage. The party has gained over 100 seats and won about a quarter of the vote.
In an article for ITV News, the Conservative MP Adam Afriyie calls for a guarantee on an in-out EU referendum to deal with the UKIP threat.
Liberal Democrat leader Nick Clegg has played down the threat of UKIP as British politics' third party, saying Nigel Farage stands no chance of gaining power.
Latest polling data suggested the Lib Dems would claim just 13 per cent of the vote at a General Election, behind Farage's party.
But Mr Clegg told Daybreak "there is two years to go" until the next election and added: "No one seriously thinks - even the greatest advocates of UKIP - that Nigel Farage is going to be the next Prime Minister."
UKIP will win the next elections for the European Parliament, UKIP economics spokesman Godfrey Bloom said today, after leader Nigel Farage confirmed that he will stand for parliament in the 2015 general election.
"It was, I reckoned, a no brainer that we were bound to come first in 2014 and that's clearly, I think, what's going to happen," he told the Sunday Politics.
He said the party's priority was now to get elected to the Westminster Parliament so they could challenge Mr Cameron directly.
"I'd love to see Nigel Farage get at his throat at Prime Minister's question time. That's our ambition," he said.
UKIP leader Nigel Farage has confirmed that he will stand for parliament in the 2015 general election.
Speaking on the BBC's Andrew Marr show, he said: "June 2014 we have a European election that is the day which I believe UKIP can cause an earthquake in British politics.
"I want to lead the party into that thereafter yes I will stand for a seat in 2015.
He added that his party was "not some little pressure group that will go away."
UKIP's success local elections has led one defeated Conservative councillor to question the direction David Cameron has taken the party.
Alexis McAvoy told ITV News that the Conservative leader needs to appeal to traditional Conservatives, and hear their concerns about immigration and the European Union.
UKIP's biggest local election success was in Lincolnshire, where the party now has 16 councillors and is the main opposition to the Conservatives.
UKIP previously held none of the council's 77 seats following the 2009 local election.
The Conservative Party fell three seats short of retaining overall control after losing 25 wards to leave them with 36.
Martin Hill, the council's Conservative group leader, said David Cameron and the Coalition "have got to show more that they are not just taking rural and suburban areas for granted".
ITV News Correspondent Rupert Evelyn reports from Lincolnshire:
Labour leader Ed Miliband said he is "very pleased" his party has won both mayoral elections in Witney and Doncaster:
Very pleased that both Witney and Doncaster mayor have gone Labour... on my way to congratulate @ros4doncaster
Witney is David Cameron's constituency while Doncaster North is Miliband's.
UKIP has sent shockwaves through the political landscape after it won 139 seats at yesterday's local elections.
UKIP may have been branded "clowns" by Conservative minister Ken Clarke, but it's party leader Nigel Farage who is having the last laugh, with many of the wins coming at the expense of the Tories.
Warning: This report contains flash photography.
UKIP has gained 139 county council seats while the Conservative Party has lost 335.
Labour also gained seats at the local elections - 291 - while the Liberal Democrats lost 124 seats.
The Conservative Party has held Northamptonshire County Council with 36 seats:
The final results are: Conservative 36 Labour 11 Liberal Democrat 6 UKIP 3 Independent 1 #NCCVote2013