Danny Alexander has said the Liberal Democrats' poor performance at the Newark by-election was a "deeply disappointing result," but was due to "tactical voting" from the party's supporters.
The Chief Secretary to the Treasury was asked why the party had slumped from a 20% share of the vote to just 2%, a result that saw them lose their deposit.
He put some of the decline down to voters not wanting to see Ukip win the seat from the Tories, saying: "The last thing our supporters wanted was to be represented by Ukip in the House of Commons, therefore there was a lot of switching to other parties."
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."
Ukip leader Nigel Farage conceded his party had been defeated during the by-election, but hailed the result as Ukip's "strongest ever by-election performance".
Speaking after the result, Mr Farage said: "I think there'll be an awful lot of Conservatives with a majority of less than 10,000 who will look upon this result in sheer horror."
But he admitted he would have liked to have done better in Newark.
"Yes, I mean the majority's halved, but nonetheless for Ukip it's still a good night's work," he said.
David Cameron has hailed the Newark by-election result as "very good for the Conservative Party" but he said the Tories needed to "work between now and the next election" to win back voters from Ukip, who came out second in the by-election.
The PM was speaking in Bayeux, France ahead of D-Day commemoration events.
Asked how he would win back support from Nigel Farage's party he acknowledged the challenge posed by Ukip:
"The job isn't finished yet but we are on the right track, let's stick at it."
Prime Minister David Cameron has hailed the new Conservative MP of Newark, Robert Jenrick on Twitter by saying he will work to deliver a "brighter future".
In @robertjenrick the people of Newark will have an MP who will fight for them and work to deliver a brighter future for all.
After the Conservatives win in the Newark by-election, Labour candidate Michael Payne has revealed he will push Robert Jenrick all the way "to the General Election."
Robert Jenrick, the Conservative candidate, won the Newark by-election with Ukip coming in second and Labour in third.
Speaking this morning, Labour's candidate spoke of how proud he was of his party's campaign during the by-election.
He said: "While this was always going to be a tough by-election, I am extremely proud of the campaign that Labour has fought.
"In the months ahead, I'll continue campaigning on those issues and holding Robert Jenrick to account right the way through to the General Election."
Robert Jenrick saw off the threat from the eurosceptics to win the parliamentary seat for his party, but the Tory majority was cut significantly from from 16,152 to just 7,403.
Ukip surged from a distant fifth in 2010 to second, pushing Labour into third place while Liberal Democrat support was obliterated, leaving the candidate trailing in sixth place
Ukip MEP Roger Helmer increased the anti-European Union party's support from just 1,954 votes in 2010 to 10,028.
The Conservative Party has have won the Newark by-election.
ITV News Correspondent Paul Brand has tweeted: