David Cameron has hinted at more tax cuts if Conservatives win next y ear's general election, telling the party's spring forum: "As long as I am leader of this party, wherever we can cut people's taxes, we will do".
Mr Cameron told delegates in London that Britain was now "coming back" after the recession but warned that recovery and tax cuts were "in the balance" if Labour wins the May 2015 poll.
Urging Tories to fight the upcoming campaign - as well as elections to councils and the European Parliament on May 22 and the Scottish referendum in September - with "clarity and boldness", Mr Cameron warned of "truly stratospheric" risks if Labour wins back power.
Mr Cameron said there was "a feeling that after a long and cold winter, Britain is coming back".
But he warned: "Be in no doubt, all of this is in the balance on May 7 2015.
"Those jobs that have been created here, they can go overseas. The tax cuts, they can be reversed. The deficit can rise up again.
"And most important, the hopes and ambitions people have for their future, the sense that Britain is a country moving forward, all this can evaporate."
Branding governments who waste tax money "white collar thieves", Mr Cameron said: "We are Conservatives. We believe in low taxes and as long as I am leader of this party, wherever we can cut people's taxes, we will do."
The speech came amid a tussle between the Liberal Democrat and Conservative sides of the coalition over who should get the credit for the flagship tax cut raising the threshold for income tax to £10,000, which comes into effect this weekend.
Mr Cameron said that tax cuts which gave businesses and families "security and peace of mind" and were possible because "the Conservatives - the party of low taxes - are in Government".
But Lib Dems pointed out that the £10,000 allowance was a key plank of the Lib Dem manifesto at the 2010 general election, when it was dismissed by Mr Cameron as unaffordable.
Treasury minister Danny Alexander hailed it as "a Liberal Democrat tax cut worth up to £705 for over 26 million working people".
Mr Cameron also highlighted the £2,000 National Insurance break for businesses which comes into effect this weekend, writing to almost two million companies and hand-delivering the first letter to a London butcher.
But Labour claims that, despite these tax cuts, the average British household will be £974 a year worse-off by the time of next year's general election as a result of tax and benefit changes introduced by the coalition.
Mr Cameron hailed the record of his "great team" of Conservative Cabinet ministers, including George Osborne, William Hague, Michael Gove, Theresa May and Jeremy Hunt, but made no mention of beleaguered Culture Secretary Maria Miller, who is under fire over her expenses.
He said Tories would fight the council elections on the message "good local government that costs less" and the Euro-polls on the three words: "Britain's national interest."
To loud applause, Mr Cameron said: "Britain is coming back. We always recover from adversity, whether it was Churchill standing up to the Nazis or Thatcher nursing the sick man of Europe back to health.
"This is the comeback country of world history, and we're doing it again, coming through a hard time and coming through stronger.
"Brilliant, brave, buccaneering, beating the odds.
"Great Britain is coming back and everyone here can be so proud of that."
Labour vice-chairman Michael Dugher said: "David Cameron lives on another planet. His claims that people are better off show how out of touch he really is.
"Britain isn't coming back - but Britain's living standards have gone backwards. Under the Tories this is the slowest recovery for 100 years.
"He talks about tax changes but fails to mention that figures from the independent Institute for Fiscal Studies show that by next year households will be on average almost £1,000 a year worse off because of changes since 2010. This comes on top of the fall in real wages that means working people are £1,600 a year worse off than they were when David Cameron entered Number 10."
Mr Cameron took a swipe at UK Independence Party leader Nigel Farage, accusing him of "failing to stand up for Britain".
The Prime Minister told delegates: "Ukip cannot change a thing in Brussels. N ot my words, the words of their leader. Nigel Farage has admitted that, I quote, 'Ukip cannot change a thing'.
"And frankly they barely even try. Even when they do bother to turn up to vote, they don't stand up for Britain."
The Conservative message was that "Labour and the Lib Dems won't give you a say in Europe, Ukip can't change anything in Europe, it 's only the Conservatives who can deliver real change in Europe and, yes, i t is only us that will give the people of Britain that in/out referendum", he said.
But Mr Farage retorted: "If David Cameron thinks Ukip can't change a thing he'd better think again.
"Without Ukip snapping at the heels of the political establishment, the British public would be forced to accept the status quo and democracy would be denied any kind of voice.
"If he thinks he can reform the European Union from the inside, how does he explain the 55 objections raised by the UK in the Council of Ministers that have been ignored? Or the comments from the Commission President that the British Prime Minister has tabled no proposal for any significant change?
"We are the party that believes to notably improve our relationship with the EU first we must leave. He represents the vain belief that he can somehow play orchestral conductor to all 28 member states, the Parliament and the European Commission.
"It's about time he justified his arguments with an open and honest debate. But if he is too gutless to face Ukip in the UK, how is he going to single-handedly take on the EU in Brussels?"