A protest song that repeatedly accuses Theresa May of lying and mocks her claims for strong and stable leadership is heading to the top of the charts, days after it was released and a week before the general election.

Liar Liar was released last Friday as a remix of a reggae song by Captain Ska, a six-piece anti-austerity band. It already tops Amazon’s listing for songs downloaded in Britain and the iTunes UK chart, despite receiving no airplay from radio stations because of impartiality guidelines.

Until the election on 8 June, all proceeds from downloads will go to food banks and the People’s Assembly anti-austerity campaign.

An accompanying video features the prime minister’s U-turns on article 50, the “dementia tax” and her calling a snap election, and has been viewed more than a million times.

The song is seventh in the official singles chart and is expected to go higher when the chart is updated on Friday. Campaigners from the People’s Assembly are planning to protest outside Broadcasting House on Friday during Radio 1’s chart show to demand that the BBC play the song.

The song includes several clips of May’s speeches, with the chorus: “She’s a liar, liar, oh, she’s a liar. No you can’t trust her, no, no, no.” It also shows May holding hands with Donald Trump and chuckling in the House of Commons.

The first verse attacks May’s record on schools, the NHS and inequality. The lyrics are:

We all know politicians like telling lies

Big ones, little ones, porky pies

Saying they’re strong and stable won’t disguise

We’re still being taken for a ride

Nurses going hungry, schools in decline

I don’t recognise this broken country of mine

They’re having a laugh, let’s show them the door then

Cut the rich, not the poor.

The song does not explicitly back Labour, but the video ends with captions saying: “On 8 June, Tories out.”

Producer and writer Jake Painter, who founded Captain Ska in 2010 as a musical protest to austerity, told the Guardian he was “overwhelmed” by its success. “[I’m] just so glad the musical message is resonating.”

Asked if he was backing Jeremy Corbyn in the election, he said: “[I] just want to kick the Tories out however possible.”

He added: “I’ve been in the industry for 15 years and Captain Ska is the result of my total frustration with the apathetic response to the most rightwing government in decades.”

The band are planning a London performance next Wednesday 7 June, the eve of the election, at Brixton Jamm with ticket details to be released on the band’s Facebook page.

Captain Ska’s Twitter feed has cheered Liar Liar’s progress up the charts and May’s slipping poll lead.

In a Facebook update, Captain Ska said: “Just a quick one to say thanks so much everyone. I’m so overwhelmed by the response and so happy that we’ve raised so much money for food banks and the People’s Assembly. There’s a big gig happening on Wednesday 7 June in London, I promise tickets will be announced very shortly.”

Previous tracks by the band include What’s the Point of Nick Clegg?, War Crime, Shame On You and US Healthcare Explained.