Labour leadership contender Owen Smith has denied allegations of supporting privatisation of the NHS.
Smith, who was left as the sole challenger to Jeremy Corbyn after Angela Eagle pulled out on Tuesday, previously worked for US drug company Pfizer and pro-Corbyn critics have accused him of actively pushing for the privatisation of some NHS services.
An anonymous "senior Corbyn ally" is quoted by The Times as saying: Bring on the Blair-lite candidate. Our members won't be fooled by a TV-savvy turncoat who lobbied for big pharma and Tony Blair."
"It's clearly a lie," Mr Smith told ITV's Good Morning Britain. "I believe in a 100% publicly-owned NHS free at the point of use - I always have done.
"I have never advocated the privatisation of the NHS. I'm a south Wales MP who grew up believing that our greatest achievement came out of south Wales, and Aneurin Bevan created the NHS."
Smith said he had had his arm twisted in the decision to run against Corbyn, whom he had previously supported, after receiving more than 30 phone calls from colleagues urging him to stand.
He said Labour was in danger of "splitting apart and being completely destroyed" under Corbyn's "watch".
The former shadow work and pensions secretary, comparing himself to the Duracell bunny, said he was the man to unite the party and present a radical alternative to the Tory government.
"I'm told that the Labour Party is only going to have three head-to-head hustings between myself and Jeremy during this debate," he said.
"I don't think that's enough - I want to debate with Jeremy in every town, every village hall, every city in Britain. I'm like the Duracell bunny, I want to take him on everywhere we go."
Asked if he would authorise the use of nuclear weapons if he became prime minister, Mr Smith said: "Yes is the unfortunate answer to that because, if you are serious about defence and serious about having a nuclear deterrent, then you have to be prepared to do that."
The Labour MP also spoke of his past as a BBC journalist, and opened up about an infamous gaffe when he dialled 999 instead of the police press office after he was asked to get an official response to a developing crime story.
Smith said there was a bit of a culture of bullying on the radio show he had been working on, and that he made a "silly mistake" which was "very embarrassing with colleagues at the time".
"There was a bit of a, to be honest, a culture of bullying."
He added: "It was very embarrassing with colleagues at the time, and it was very embarrassing when the police did make a complaint about it."
Meanwhile, Jeremy Corbyn has won his bid to personally fight a legal action aimed at overturning the Labour Party's decision to guarantee him a place on the leadership ballot.