DUBUQUE, Iowa – Jeremy Corbyn's influence is spreading to the US.

Democratic presidential candidate Bernie Sanders has said he is aware of the rise of the left-wing British MP, currently favourite to win the Labour party leadership contest, and says he sees parallels between his campaign and the current state of left-wing politics in the UK.

"Whether it's the UK or here in the US, people are sick and tired of establishment politics," Sanders told BuzzFeed News on the campaign trail in Iowa. "They are sick and tired of a politics in which people continue to represent the rich and the powerful."

For a British observer, watching Sanders is like watching Corbyn two months ago – a candidate drawing enormous crowds but still dismissed as an unelectable crank by the mainstream media and political establishment. In the UK that changed when it was realised that the enormous rallies and social media backing were actually turning into real support at the polls.

Just as Corbyn unexpectedly took the lead in the Labour leadership, so Sanders is surprising the Democratic establishment by leading Hillary Clinton in early polls in Iowa and New Hampshire.

"Our campaign has taken the political establishment by surprise," Sanders shouted at a crowd of 500 packed into a sports centre in the Iowan town of Dubuque. "Three and a half months ago they asked if there was an appetite to stand up to the billionaire class. Guess what? Turns out there is!"

Watch both Sanders and Corbyn speak, and the parallels are easy: Both are self-described socialists who spent decades on the fringes of politics and reluctantly entered the race to lead their party three months ago. Both have the demeanour of a university protester approaching retirement and unexpectedly found themselves capturing the attention of young supporters who were disillusioned with the mainstream left's choice of candidates.

They both get massive cheers for bringing up their votes against the Iraq war, for saying that inequality is a scourge, big banks need to broken up, public healthcare needs defending, and university tuition fees should be free. Sanders is less radical than Corbyn's unashamed socialism, but both have a message packing out massive rallies of grassroots supporters in unexpected places on both sides of the Atlantic.

"Every other candidate seems to be the same and connected with big money," said Sanders supporter Mark Weis, a lifelong Democrat who won't vote for Clinton because of her establishment connections. "What appeals to us is he isn't accepting money from big business. If Bernie doesn't make it we won't vote for Hillary."

Sanders and Corbyn supporters both want the real left-wing deal, believe they've found it, and are willing to reject any alternatives.

But unlike the favourite to be Labour leader, Sanders supporters are honest about his chances of taking the nominations. While Sanders supporters cheer his refusal to solicit large financial donations, it's likely to hinder his chances of beating Clinton in the long-run.