As the crowd gathered in New York’s Washington Square Park on Monday night, confused journalists and Hillary supporters asked each other for information.

“Do you know what we’re waiting for?” asked a man. “Is it going to be some faceless college professor telling us how to vote?”

The small stage being constructed in the centre of the park’s fountain, and the security detail standing by, hinted at more – and at 7.30pm, just as the rumours began to start, we got our answer. The queen of pop had come to lend her support to the Clinton campaign.

“This concert is about unifying us,” said Madonna as she took to the stage, clutching a red guitar and flanked by a musician and her son David. “How are we going to keep America great?

“We are going to elect a president who does not discriminate against women, who does not discriminate against the LGBT community, who does not discriminate against people of color, that does not want to build a wall around our country and separate us from the rest of the world. This is a concert about peace.”

Apologising for her guitar skills, she began an acoustic set, stopping between each song to give missives against the Republican candidate. “No way, motherfucker,” she declared, as she launched into Express Yourself.

For the astonished audience, it was a once-in-a-lifetime opportunity to sing along with Madonna to some of her biggest hits, including Don’t Tell Me and Like a Prayer – but her cover of John Lennon’s Imagine was the crowning moment: a cathartic sense of unity ahead of the next day’s uncertainty.

Introducing the song, she called Lennon one of the “angels who have been sent to this universe to bring peace on Earth”.

“What about us?” called a man.

“What about us?” she answered. “We’re here to keep the fire going.”

Earnest speeches about love were peppered with a caustic sense of humour. When asked to turn to her right during a song, Madonna quipped: “I’m a top and a bottom, but I don’t do sides.” Later she said: “Let’s hope I get invited to the White House.”

The concert was performed in the round, and those who surrounded her with Hillary signs, who had come for a pre-election day boost, were not disappointed. “Tomorrow’s the big day,” Madonna told us, expertly pausing for cheers and responses. “Do we want to become the laughing stock of the planet?”

Finally, after a medley that merged Pete Seeger’s If I Had a Hammer into Madonna’s Rebel Heart, she called, “Save this country, vote for Hillary Clinton.”

Then she was gone, and the crowd turned to find themselves in the middle of the Pantsuit Power dance flashmob, performing the Clinton-themed dance first encountered in a viral video by film-makers Celia Rowlson-Hall and Mia Lidofsky.

Next to the space where Madonna had been, a man dressed as Abraham Lincoln posed for selfies with passersby, and the stencil artist behind the I Feel Like Hillz street art campaign created fresh artworks for people to take home, as originators of various pro-Hillary groups and online movements introduced themselves to each other.

It was the pop-up rally that no one expected, setting a cautious mood of optimism among New Yorkers hoping to see the first female president elected on Tuesday. And it was a final reminder of Clinton’s top-tier pop endorsements, which includes a holy trinity of divas: Madonna, Beyoncé and Adele.

If they can’t save us, well, then maybe we can’t be saved.

The Guardian