Jeremy Corbyn has insisted Labour can win a snap general election, despite polls showing the party trailing the Conservatives by as much as 18 points.
But the declaration of confidence came only after the Labour leader was asked twice whether he would welcome an immediate election and six times whether he could win it, in an increasingly tetchy TV interview on BBC Two's Victoria Derbyshire programme.
The prospect of a snap election has been floated by former foreign secretary Lord Hague, who said it would give Theresa May a "decisive" majority to help her get Brexit through.
But Downing Street made clear that the Prime Minister does not believe there should be an early poll.
Mr Corbyn's comments came as prominent Labour supporter Stephen Hawking called for him to stand down as leader, describing him as a "disaster" for the party.
And they follow a poll on Monday which suggested as many as half of Labour members think he should quit before the election scheduled for 2020.
Asked whether he would welcome an early election, Mr Corbyn told Derbyshire: "I want to see a different government. I don't want to see this Government in office."
But when she pressed him repeatedly over whether he felt he could win an election, he replied: "We will take our case out, we will do our very best to win the election.
"Nobody knows the result of a general election before they go into it, but we do know we have a very strong, moral and just case to put to this country of the kind of country we could be."
It was only when Derbyshire demanded a "yes or no" answer to the question of whether Labour could win that Mr Corbyn replied: "Listen, you've asked me the question many, many times.
"How many times do I have to tell you, we are taking our case out there to win because we believe we can win."
The Labour leader blamed "media obsession" for reports of disunity within his party and insisted observers should not "underestimate" the scale of support it enjoyed in the country.
"We're going to take our case out to the country," he said. "We're very confident of the support we can get in order to win the election, to take our case to the British people.
"Don't underestimate the support there is for the Labour Party, don't underestimate the anger there is out there at the levels of inequality and injustice within our society.
"We will expose all of that - that's where our case is very, very strong."
Following shadow chancellor John McDonnell's warning of a "soft coup" planning to oust Mr Corbyn, the Labour leader issued a plea for unity from MPs.
"I'm asking all Labour MPs to get behind the strategy we are putting forward, get behind an investment-led economy, get behind our opposition to what this Government is doing in creating greater inequality in our society," Mr Corbyn told Derbyshire.
"We have a very large party membership out there campaigning week in, week out, and we have council and mayoral elections coming up. We are all going to be together on those doorsteps, winning those elections.
"I think there's a media obsession with the internal workings of the Labour Party. Let's get out there on the policies, let's get out there united as a party determined to change the way in which people live in our society so they can live better lives. That's what politics is really all about."
But Prof Hawking - who has publicly backed Labour's Cambridge MP Daniel Zeichner and was pictured on his campaign leaflet at the 2015 general election - said it was time for Mr Corbyn to stand down for the good of the party.
The Cambridge University academic told The Times: "I regard Corbyn as a disaster.
"His heart is in the right place and many of his policies are sound but he has allowed himself to be portrayed as a left-wing extremist.
"I think he should step down for the sake of the party."
The acclaimed physicist's intervention is the latest sign of unease within Labour ranks after Mr McDonnell suggested there was a "soft coup" being mounted against Mr Corbyn.
Mr McDonnell, a key ally of the leader, attempted to smooth over divisions at a meeting of the Parliamentary Labour Party on Monday night, telling MPs that Labour unity is "what the Tories fear most" ahead of Wednesday's Budget.
But Labour MPs Wes Streeting and Peter Kyle raised concerns with him, apparently referring to his "soft coup" claims.
Mr McDonnell's spokesman said his "element of contrition was about not just that, but over the past" as well.
One Labour MP present at the meeting said Mr McDonnell did not apologise for claiming last week that elements in the party, in alliance with the "Murdoch media", were intent on "destroying" Mr Corbyn.
But the shadow chancellor's spokesman said: "His element of contrition was about not just that, but over the past, from the summer when he chaired Jeremy's campaign, and also since then, it was about putting most importantly and front and centre that the Labour Party is united on this front (the Budget)."