Nick Clegg to outline Lib Dems' tax allowance pledge
Lib Dem leader Nick Clegg is expected to set out more details of how the party would fulfil its pledge to raise the personal tax allowance to £12,500.
In a series of interviews, he is expected to say that, if the party were in government after the election, the first budget would include that policy.
A day before his conference speech, it is thought he will explain how the Lib Dems would pay for the plan.
He has criticised his Tory coalition partners for offering unfunded cuts.
It is also understood Mr Clegg will repeat his party's promise to raise national insurance thresholds in due course.
The Liberal Democrats' policy on income tax represents an increase of £2,000 in the tax thresholds that will apply at the time of the general election next May.
It was first announced in the spring and BBC political correspondent Iain Watson says there was consternation within the party when the Conservatives offered to make the same increase at their party conference last week.
Our correspondent says Mr Clegg wants to emphasise that his party's priority in government would be to help those on lower incomes rather than higher rate taxpayers, who were also offered the prospect of a lower tax bill by the Tories.
It comes after Mr Clegg indicated at the weekend that taxes "must" be increased on higher earners after the next general election, in order to cut the deficit.
Meanwhile, despite speculation that the Lib Dems could enter into another coalition government after the election, Mr Clegg has indicated the experience has been difficult for him and the party over the past five years.
Speaking on BBC Two's Newsnight programme, the deputy prime minister said the news conference held in Downing Street's rose garden after the coalition was formed in May 2010 had given a "slightly false impression" right from the very start of the coalition between the Tories and the Lib Dems.
He said: "I think [there was a] sense of kind of chumminess, if you like, that may have been given just because it was a sunny day and we gave a sort of positive, relieved press conference as number one and two in the new government."
He went on to criticise both the Conservatives and Labour for their behaviour during the Alterative Vote referendum in 2011 on changing the way MPs are elected - a policy which the Lib Dems had fought hard to put on the joint coalition plans for their first year sharing power.
Mr Clegg said that the Conservatives and Labour fought "ruthlessly" to protect their vested interests in the ballot over whether to ditch Britain's first-past-the-post electoral system.
He said: "Clearly, the way in which the Conservative party decided to conduct that campaign - in a way which was so unnecessarily personal - they didn't need to do that....
"It was, I thought, a totally gratuitous thing. But, in a sense, it has been repeated since then."
He said that although Labour leader Ed Miliband supported AV he "barely lifted a finger to actually make the case".