Theresa May was accused of running scared after dodging a TV debate with the leaders of rival parties.
Both the Prime Minister and Labour leader Jeremy Corbyn turned down the invitation to take part in the ITV Leaders' Debate in Salford.
As the debate got under way, Labour leader Jeremy Corbyn tweeted: "Theresa May, why not debate me?
"The public deserve to see a debate between the only two people who could form the next government."
Scottish First Minister and SNP leader Nicola Sturgeon, Liberal Democrat chief Tim Farron, Ukip's Paul Nuttall, Plaid Cymru's Leanne Wood and Green co-leader Caroline Lucas showed up for the prime time debate.
Ms Wood challenged Mrs May over her decision to miss the debate, using her opening statement to say: "I have a message for the Prime Minister, who I'm sure is watching tonight.
"You may be too scared to come here tonight, for your U-turns to be highlighted, for your cruel policies to be exposed. You want this election to only be about Brexit because that means you avoid talking about the real issues like the NHS, the economy and the cuts you have made to our public services.
"That's weak leadership - weak and unstable.
"I hope all of us here tonight will show you that real leadership means being willing to defend what you stand for, not hide from it."
Ms Lucas used her opening statement to insist the UK can cope with the serious challenges it faces.
"Never in my lifetime has our future felt so uncertain. Brexit, climate change, an NHS in crisis," she said.
"But when people come together and reach for a bigger future, we have shown we can change the course of history."
Ms Sturgeon said only her party can provide a strong Scottish opposition to a Tory government in Westminster committed to an "extreme" Brexit.
She added: "The next few years will determine the kind of country we become. We need strong opposition holding a Tory government to account, keeping them in check and standing up for the values we hold dear: values of social justice, tolerance and community.
"The more seats the SNP wins on June 8, the stronger Scotland's voice will be."
Ukip leader Paul Nuttall said only his party is "truly committed to the Brexit that people voted for" in last year's referendum.
Only his party is committed to cutting immigration and slashing the foreign aid budget "that is costing you, the British taxpayer, around £30 million every single day", he added, promising extra funding for the NHS instead.
"Brexit would never have happened if it wasn't for Ukip," he said.
"We have taken you so far. Elect Ukip MPs and give us the tools to see this through."
Mr Farron said he is determined to stop the return of a "heartless Conservative government".
He warned: "Theresa May - backed by Nigel Farage and Jeremy Corbyn - is going for an extreme Brexit deal that will damage our future for generations."
Insisting "a brighter future is possible", he added: "Don't give up. The Britain I love is not lost yet."
The leaders soon clashed over Brexit, with Ms Lucas issuing a challenge to the Ukip leader on holding a final vote on the negotiated deal.
She also hit out at Labour, which she said "basically gave them (the Tories) a lift to the bank" to cash "a blank cheque" on Brexit.
Mr Nuttall insisted Ukip still has a role to play, adding: "I don't believe that she (Theresa May) will get the best deal possible for Britain, I believe she will begin to backslide.
"I think she will backslide on fisheries, I think she will sell out fishermen once again like a former Tory prime minister did in Ted Heath.
"I think there will be some sort of dodgy deal over freedom of movement as well and I think she will capitulate and we will pay a divorce bill."
Ms Wood said Wales had been disregarded after Brexit, saying: "Gibraltar has had more attention than Wales has had, so it's vital we have a strong team of Plaid Cymru MPs to advocate for Wales's national interests and to make sure that the Tories don't get away with an extreme Brexit that would cause serious harm for many people in many communities throughout the UK."
Ms Sturgeon said people should unite against the pursuit of a "hard, extreme Brexit" which she claimed would hit more than 80,000 jobs in Scotland.
Mr Nuttall said there was a "big world out there" beyond the EU to trade with, including "the Anglosphere and the Commonwealth".
"This is where our future lies," he said.
As he clashed with Ms Wood he got her name wrong, calling her "Natalie" - the Plaid Cymru leader shot back: "I'm not Natalie, I'm Leanne."
Paul Nuttall has called two of the three women on the panel Natalie. None of them are called Natalie. #itvleadersdebate— Daniel Hewitt (@DanielHewittITV) May 18, 2017
Mr Farron, whose party is committed to a second referendum, said: "Somebody will sign off that deal, it will either be the politicians or the people. I trust the people."
Ms Lucas defended the "huge contribution" made by immigrants: "Those people in our country are our lovers, they are our families, they are our plumbers, our doctors.
"They make a vital contribution to our society and the idea that we are going to be a better off society by closing the door to immigrants is just clearly wrong."
But Mr Nuttall said there were "simply too many people coming to the country" with the equivalent of the population of Newcastle added to the population last year.
Ms Sturgeon said: "The hard reality is our economy needs migration from the EU. In Scotland alone, EU migrants contribute £7 billion every year."
She added: "Public services are under pressure. That's not the fault of migrants, that is the fault of the austerity agenda pursued by the Tories."
On the NHS, Ms Wood said health and social care should be considered together, but more funding is needed.
"The wealthiest in society should stump up a bit more," she said.
Mr Nuttall blamed immigration for placing pressures on the health service and promised a funding boost by cutting foreign aid from the current 0.7% of gross national income target to a 0.2% level.
Ms Lucas said the Greens would take the private sector out of the NHS and divert funds from the Trident nuclear deterrent to the health service.
"We think it's a no-brainer to use those funds to look after people rather than to create more weapons of mass destruction," she said.
Mr Farron spoke of his mother's death from ovarian cancer and said it is "time politicians were honest with the British people that there needs to be more money, and if there is going to be more money then we will all have to pay for it".
The Lib Dems would put 1p on income tax to raise £30 billion over the next five years to invest in the NHS and social care.
Ms Sturgeon said the SNP has increased the Scottish health budget by 40% and has integrated health and social care.
But "needless Tory cuts and austerity" are putting the NHS at risk, she warned.
Moving on to social care, Ms Wood said it was time to "stop the squabbling" over NHS and council budgets so patients could be put first.
Mr Nuttall got into hot water when he tried to reply, calling Ms Wood Natalie for the second time in the debate.
She retorted: "Who are you calling Natalie?" to which he said, "Leanne, I'm sorry."
Ms Wood replied, "You've done it twice now," and Mr Nuttal replied: "Have I? I'm sorry about that."
Recalling his grandfather's journey through Alzheimer's disease, Mr Farron called for better pay for care workers.
The Lib Dem leader said: "It's a reminder that the people who work in our social care service are brilliant people, but most of them can earn more stacking shelves at their local supermarket.
"If we care about out older people, we care about the people who care for them. That is why we are putting a penny on income tax for health."
Ms Wood echoed his concern about low pay for staff, saying many were on zero-hours contracts which she branded "a real scourge" on society.
Building up social care would take pressure off the NHS, Ms Sturgeon said, while acknowledging the challenges the Scottish Government had faced trying to integrate health and social care.
Turning to the squeeze on people's wages, Mr Farron said staying in the single market was the best long-term economic plan as it would protect jobs and wages.
Ms Lucas spoke of how a constituent was unable to buy tights to go to a job interview because the bedroom tax had been so costly for her.
She said: "That is what we have come to in the fifth biggest economy in the world. I think that is shameful.
"We can afford to look after everybody in our society if we choose to do so."
Ms Sturgeon also raised concern about "obscene" levels of poverty among children, calling for an end to the freeze on working age benefits.
She added: "Social security cuts are penalising the poorest in our society, many of them working.
"Let's bring some decency back to the social security system of this country."
Ms Lucas said: "It's unfortunate there isn't a single question to which the answer for Paul Nuttall isn't immigration."
Mr Nuttall blamed immigration for the housing shortage, saying 80,000 homes a year were "swallowed up by immigration alone".
"We are not building enough houses," he said.
The audience laughed as Mr Farron pointed out: "You'll need migrant labour."
On education, Mr Nuttall clashed with the Lib Dem leader and Ms Lucas over his support - like Mrs May - for more grammar schools.
The Ukip leader said: "I believe in academic selection. I believe that we don't have enough grammar schools in this country - we have 164 at the moment - we need more.
"But the problem that you have is that the majority of these grammar schools are in middle class areas.
"We need to get them into working class areas which then allow working class kids to break out of their communities."
Mr Farron said the Tories were choosing to spend money on free and grammar schools when headteachers were being forced to lay staff off.
"The average secondary school will lose six teachers, the average primary school two teachers. That is the decision Theresa May is making."
The argument for grammar schools was "bogus", he said, while Ms Lucas said there was "no educational evidence that suggests this is good for the vast bulk of our people".Tweets by itvnews