Mr Watson told The Guardian that the Prime Minister was guilty of "contempt for voters" by refusing to take part in a head to head debate.
British prime minister Theresa May faced laughter, jeers and heckling from a studio audience on Monday night as she struggled to answer questions about her record during a TV interview with Jeremy Paxman.
The Labour leader chose to be first up in the Battle for Number 10 show, which was broadcast by Sky News and Channel 4, after winning a coin toss.
"It is a hypothetical question", he said.
"We will make sure there is a deal".
Before that though, in the section when audience members posed the political leaders questions, May was asked by a midwife how she and the Conservative party "justify the chronic under funding of the NHS".
"We are doing the right thing in making a success of Brexit", she said, vowing to maintain her reputation as a "bloody hard woman" during talks with European Union leaders if her party wins the election and keeps power.
Mr Paxman said: "So you are prepared to walk away?"
He added: "You don't address these problems by ignoring them".
Theresa May has been accused of being a bad negotiator. She replied: "I think you have to".
"You have to. In negotiations, you have to recognise that you're not in there to get a deal at any price".
As the June 8 election looms, May and Labour leader Jeremy Corbyn are attempting to focus on issues where they believe their parties are strongest.
When asked whether it was fair that winter fuel allowance should be means-tested in England but not in Scotland, Mrs May said this was due to devolution and that the Scottish Government could make separate decisions on the issue.
He was pressed by Mr Paxman over comments he made following the Argentine invasion of the Falklands that "young unemployed men" were being sent to the South Atlantic to die in pursuit of a "Tory plot". Shot in his Ladbroke Grove neighborhood in London, Tracey adds that he is unsure if he'll ever be able buy a house but that Labour's commitment to building more homes gives him faith it could happen.
Mr Corbyn defended his description of the Palestinian group Hamas as "friends" and his comment that the killing of Osama bin Laden by United States special forces had been a "tragedy".
"We need to face up to the fact that there are going to be extra costs and we think this is the best way to handle it and I think the audience responded well to that honesty". "And he could have been", he said.
She said there was "no single measure" to change immigration figures, describing it as a "constant work".