Theresa May and Jeremy Corbyn will face a televised grilling as the General Election campaign intensifies.
The Prime Minister and the Labour leader will be quizzed by broadcaster Jeremy Paxman and a studio audience in the joint Channel 4 and Sky News show.
Mrs May ruled out going head-to-head with Mr Corbyn in a debate, so the two leaders will be questioned separately during the show.
The TV event comes as Mrs May's opponents sought to maintain pressure on her following the extraordinary U-turn over the social care policy which formed the centrepiece of her election manifesto.
Mrs May committed to a cap on costs in response to a backlash after unveiling her social care reforms, but the Tories say the limit on how much people will have to pay will not be decided until a consultation following the June 8 election.
Labour's national election co-ordinator Andrew Gwynne said Mrs May needs to answer "crucial" questions over the plans.
The Opposition demanded to know what the cap would be and how many people will be liable to lose the winter fuel allowance, worth up to £300, under Tory plans to means test it.
Mr Gwynne said: "The Tory manifesto has plunged pensioners and working people into insecurity, and left our public services facing the risk of further crisis. Meanwhile, Theresa May refuses to answer even the most basic questions on her policies."
With the Tories suffering in the polls following the criticism over the so-called "dementia tax", the Liberal Democrats also sought to maintain pressure over the issue.
Lib Dem health spokesman Norman Lamb accused the Prime Minister of "showing contempt for vulnerable older people" by refusing to spell out what the effect of the policy would be.
Even with a cap, the "dementia tax" could result in up to half the value of the average family home being put at risk, Lib Dems claimed.
According to property website Rightmove the average price tag on a home is now £317,281.
The analysis assumes 10 years of domiciliary care at a cost of £14,560 a year as well as charges including estate agent fees, deferred payment fees, interest payments and legal fees.
This would cost a total of £173,282, or 54% of the average asking price.
In a sign of the difficulties the issue has caused Mrs May's campaign, a poll suggested only one in four people (24%) name the Tories as the party they trust most to protect pensioners' interests, while 44% choose Labour and 6% the Lib Dems.
But the ORB survey for the Independent found the Tories were ahead among older people, who are most likely to vote.
Some 39% of 65-75 year-olds and 58% of over-75s trust the Tories most to protect pensioners, compared with 32% and 21% respectively who trust Labour most.
Mrs May sought to get her campaign back on track by setting out new measures to tackle domestic violence.
A new offence will allow tougher sentences to be handed down to perpetrators of domestic violence against children and a new watchdog will be established to speak up for victims and hold the police and criminal justice system to account.
The Prime Minister said: "This hidden scandal, that takes place every day in homes across Britain, must be tackled head on."
:: ORB interviewed online a total of 2,046 adults aged 18 and over throughout the UK on Wednesday and Thursday.