Nick Clegg told Liberal Democrat supporters they had won a "stunning victory" in Eastleigh, despite the "exceptional circumstances".
Prime Minister David Cameron said today that the Eastleigh by-election result was "disappointing" but he was "confident" that the Conservatives could win back support at the general election.
Liberal Democrat leader Nick Clegg has thanked party supporters after the party held the seat of Eastleigh in yesterday's by-election.
He said: "This has been a by-election we have had to fight in exceptional circumstances. Our opponents have thrown everything at us. We held our nerve, we stood our ground, we worked as a team, we went out and campaigned on every doorstep. We overcame the odds and won a stunning victory."
The UK Independence Party's Diane James, has described beating the Tories to take second place in the Eastleigh by-election was a "humongous" shock that represented a "seismic shift" in UK politics.
Conservative candidate Maria Hutchings polled 10,559 votes - more than 1,000 behind Ukip, which snatched huge chunks of the coalition parties' 2010 general election vote share, taking more than 27% of the total.
Conservative MPs have been tweeting after the party's candidate, Maria Hutchings, finished third in the Eastleigh by-election:
Gutted. Lovely woman would be great MP. Got to start work now - have a great day ! (Palin-esque)From @claire4devizes on Twitter:
Pinch punch first of the month-not the best start to the month from Eastleigh. Commiserations to Maria, stick at it thoughFrom @timloughton on Twitter:
So. Apart from all that, how's it going.....From @DouglasCarswell on Twitter:
Liberal Democrat president Tim Farron has called the Eastleigh election the most "important by-election since the war."
His party's candidate Mike Thornton won the by-election with a majority of 1,771.
Speaking to Daybreak he said the win was an "outstanding" result, that speaks volumes about the Lib Dems' place in the next general election.
The Conservative Education Secretary Michael Gove told Daybreak that UKIP's success in the Eastleigh by-election is purely down to "protest."
He said: "People from Lib Democrat ranks and Conservative, were voting UKIP because they wanted to register a sense of pain and frustration at a difficult time for the country."
Deputy Prime Minister Nick Clegg has congratulated Mike Thornton on his victory:
The leader of the UKIP party, Nigel Farage is already looking ahead to the future of his party.
Speaking to Daybreak he said this morning's result at Eastleigh was "really exciting", as the party gained so many votes from Tory, Labour and Lib Dem voters.
He said looking forward to to 2015, the party needs to focus on getting more members, and more presence in UKIP's "weaker parts of the country."
Speaking to Daybreak, Daily Mail journalist Andrew Pierce said that this morning's win at Eastleigh for the Liberal Democrats is a "complete disaster for the Conservative party."
The Lib Dems won by less than two thousand votes in the by-election, managing to hold off a UKIP surge.
The Daily Mirror's associate editor Kevin Maguire added that UKIP should be "deliriously happy" with their result, receiving more votes than the Conservative party.
He added: "It's a nightmare for David Cameron who played his Europe card, who thought that would stem the flood of Tory voters going to UKIP. It hasn't happened."