Campaigners for a British EU exit, or Brexit, criticized Prime Minister David Cameron on Monday for failing to agree to a live debate with them ahead of a referendum on June 23.
Cameron was set to answer questions from a live television audience late Tuesday, in what could prove to be one of the most important appearances in his campaign for Britain to Remain.
Cameron and Nigel Farage, leader of the anti-EU UK Independence Party, are scheduled to appear separately in the ITV programme, prompting critics to complain that the broadcaster will not host a direct debate between Cameron and his opponents.
Vote Leave, a cross-party campaign spearheaded by ministers from Cameron's Conservative Party, accused him of refusing to debate with its leaders.
"The prime minister says we need a proper debate about the facts, but he is too chicken to take on anyone from the Vote Leave campaign head-to-head," said Douglas Carswell, UKIP's sole member of parliament.
Cameron held a press conference on Tuesday to address what he said was a problem of Leave campaigners making inaccurate statements about the costs and benefits of a Brexit.
He criticized Vote Leave's claim that Britain could be forced to contribute to bailouts of eurozone nations, after accusing the group of being "undemocratic and reckless" by failing to outline its economic plans.
"Today, credible experts are warning about the risks to our economic security, while the Leave campaign is resorting to untruths," Cameron said, referring to warnings against Brexit by the head of Hitachi, the US central bank and the World Trade Organization.
"What I'm concerned about is that people are being told things that are not correct," Cameron said. "We must make this decision on the basis of facts and arguments."
He said he was looking forward to the ITV event and urged more people to vote in the referendum. Voter registration closes at midnight on Tuesday.
Carswell said Cameron's comments showed that "the In campaign is in a blind panic" after recent opinion polls suggested that Leave has caught or even moved ahead of Remain.
"David Cameron's renegotiation was a failure; no one believes he got a deal worth the paper it was written on," Carswell said. "Now people are rejecting his campaign of fear."
An ORB-Daily Telegraph poll of 800 people who said they were committed to vote put Remain on 48 per cent and Leave on 47 per cent, with 5 per cent undecided.
A YouGov-GMB poll of some 3,500 people last week found 41 per cent support Remain and 45 per cent back Leave.
Vote Leave had earlier accused ITV of bias by hosting a show with just Cameron and Farage, who leads a separate Grassroots Out campaign.
Boris Johnson, the figurehead of the Vote Leave campaign, is expected take part in at least two live televised debates before the referendum, including a BBC event with an audience of 6,000 on June 21. Cameron reportedly declined to join the BBC debate.
Ahead of Tuesday's programme, Farage said he wants "what's best for Britain: controlling our own borders, making our own laws, running our own country."
"Tonight I'm going to tell the truth about what the EU has done to the UK," he said on Twitter. "I invite Mr Cameron to do the same."