Nick Clegg revealed details of "very hostile" coalition clashes over tax policy as he accused the Tories of being "spectacularly inconsistent" in their approach to easing the burden on workers.
The Deputy Prime Minister said there had been resistance in Whitehall to his call for a "workers' bonus" tax break in the Budget but now the Tories were attempting to claim credit for his party's ideas.
Mr Clegg has pushed for the income tax threshold to be raised to £10,500, which would be worth £100 to basic-rate taxpayers.
Speaking at an event in Westminster, he said: "If you want to judge a party's commitment to fairer taxes, then one of the absolute ingredients you need to look for is consistency over time. I have been saying the same thing for well over half a decade, which is that we need to target all our tax cuts on those on low and middle incomes by raising the allowance.
"It was a Liberal Democrat manifesto promise, on the front page of our manifesto, which will finally find its way into the pay packets of millions of people next month, by raising the allowance to £10,000.
"I have said I want the allowance to go further up, I want a further workers' bonus in the next Budget so that the allowance is set at £10,500.
"I'll try and be polite on this: my coalition partners, by contrast, have been spectacularly inconsistent. At the beginning of the Parliament they were first going on about inheritance tax cuts for millionaires.
"Then they wanted to fiddle around with the upper rate of income tax. Then they wanted to fiddle around with the taxes for married couples. Then they wanted to fiddle around with taxes to give incentives to people to give up employment rights to take up shares.
"So they have got a fair amount of brass neck to now claim that somehow all they ever wanted all along was to see the allowance go up, because that's not what they said in public and crucially it's not actually what they said in private either.
"I've had to drag the Conservative Party kicking and screaming, in every single Budget negotiation - by the way, not least recently. When I talked about wanting to see this extra workers' bonus, there was a very hostile reaction behind closed doors in Whitehall from my Conservative coalition partners.
"So I'm delighted that everybody is now scrambling to share authorship of a Liberal Democrat idea but I would just ask for my coalition partners, indeed anybody else, to be consistent in what you say in public and what you say in private and also consistent on what you say over a long period of time on tax."
Prime Minister David Cameron is expected to hint at tax cuts in the March 19 Budget, by indicating that efforts to cut Whitehall waste will put money back in people's pockets.
In a speech, he will say that "every bit of Government waste we can cut, every efficiency we can achieve, is money we can give back to you".