Jeremy Corbyn urged Theresa May to call another general election during a speech to cheering supporters at Glastonbury Festival.
The Labour leader addressed thousands of fans, many wearing t-shirts bearing his name, at the event's Pyramid Stage and Left Field Tent.
He met festival founder Michael Eavis, 81, posed for pictures with staff at the site in Pilton, Somerset, and enjoyed a vegan lunch at the Greenpeace area.
Fans surrounded his Land Rover Discovery and chanted "Oh, Jeremy Corbyn" to the tune of the White Stripes' Seven National Army.
That chant, along with "Corbyn, Corbyn", has been a familiar sound around the 900-acre site since the gates opened on Wednesday morning.
Mr Corbyn, who had not attended the festival before, introduced US hip hop duo Run The Jewels before his Left Field tent speech.
"I simply say to Theresa May, if she has the time this afternoon to be watching Glastonbury, we are ready for another election as soon as you like," he said.
"We are on it. We are ready for it. This isn't a young versus old thing as Theresa May seems to think it is.
"Thirteen million people who came to vote for us on June 8 did so for a purpose, for a reason.
"Every indication we have got is there is an awful lot more people that have come to the same conclusion in the two weeks since the election."
Mr Corbyn said young people were told the "future doesn't really belong to them" while old people were made to a feel "a burden" whose homes would be taken off them.
He described issues such as gender equality and racism as having a "long way to go" and praised social media for helping people engage with each other.
"We can't go on destroying, damaging, polluting and degrading our planet at the rate that we are," he added.
"None of us would be afraid to pick up the phone to Donald Trump and say 'Donald, you are wrong on the Paris climate change talk'."
In another swipe at Mr Trump, Mr Corbyn said: "On the wall that surrounds this festival and there is a message on that wall for President Donald Trump - build bridges, not walls."
Some supporters were in tears as the Islington North MP delivered his speech, including when he spoke about the Grenfell Tower fire in London.
"Not so long ago we saw Grenfell Tower, a towering inferno in the middle of the richest borough in the country," he said.
"People living in poverty, living in danger, in a place that simply went up in smoke.
"Not one of those people should have died.
"That fire was wholly and totally preventable."
He said tenants who tried to raise safety concerns were "utterly ignored because they were tenants, because they were poor people, because they were working class".
The Labour Party will be voting against the Government's programme next week and putting forward an alternative approach, which will be put to parliament, he insisted.
"We are going to push the whole way, the whole time," he added.
Mr Corbyn joins Labour faces including deputy leader Tom Watson, Yvette Cooper and Ed Balls, as well as John McDonnell, at the festival.
The shadow chancellor will be part of a panel discussing whether democracy is broken at the tent on Sunday.
Glastonbury Festival is being headlined by Radiohead, Foo Fighters and Ed Sheeran but Mr Corbyn has appeared on fans' flags, t-shirts, leggings and necklaces.
A sand sculpture on the site depicts him dressed in fox hunting garb, riding a fox through fields of wheat towards Mrs May.
During Friday's headline slot, Radiohead frontman Thom Yorke muttered: "See you later, Theresa. Shut the door on the way out."
In an interview with on-site newspaper the Glastonbury Free Press, Mr Eavis said he was "thrilled" with Labour's result at the general election.
"I think he has a fundamental sense of justice, of real political change, of being anti-war and anti-nuclear," he said.
"That's what we've spent our lives campaigning for too."