Corbyn's key theme is that decades of unbridled free market capitalism in Britain has created a capitalist elite at the expense of working people, who have seen public services slashed and aspirations dampened.

The 70-year-old Corbyn presents himself today much as he did when he was a little known politician on the backbenches of Parliament: as a slightly rumpled figure battle-hardened by decades of jousting against capitalism and big business.

The only obvious change has been the addition of new suits and ties so that he doesn't look under-dressed when confronting his main rival, Conservative Prime Minister Boris Johnson, in parliament or in televised debates.

While Johnson has taken his party to the right, Corbyn has tacked to the left and endured the departure of some prominent Labour figures turned off by his approach to Brexit and the anti-Semitism that some feel has developed in the Labour Party.

Corbyn, who shocked the political establishment by seizing control of the Labour Party in 2015, has not changed his approach in a bid for more support from the centre.

He vehemently rejects the "New Labour" business-friendly policies that help propel fellow Labour member Tony Blair to three consecutive election victories.

Instead Corbyn has proudly placed the party in the European socialist tradition, endorsing a platform that would give the state a much bigger role in redistributing wealth to the working classes.

While Johnson is fond of boasting that Britain is the greatest place on earth to live, Corbyn usually describes it as a country where millions have been left behind.

He enjoys a strong core of support in the party, as the "Oh Jeremy Corbyn" chants during his speeches have made clear.

But it's not clear that he's been able to broaden that base enough to win a majority in parliament, even though he fared better than expected in the 2017 election, which saw Labour finish a strong second to the Conservatives.

Corbyn's core message deals with Britain's cherished yet struggling National Health Service, created by a Labour government in 1948. He warns that Johnson will put parts of the medical service up for sale in trade talks with the United States, betraying millions of Britons who rely on the free health service.

It's an issue that strikes home for many who are concerned with the deteriorating standards in UK hospitals and fearful that high US health care costs may soon be mirrored in Britain.

Corbyn is also promising the nationalisation of some rail and energy services, as well as free broadband internet, child care and university tuition.

He has railed against Britain's billionaires, arguing they are proof of the rising inequality in the country, and demanded that big tech companies like Google, Facebook and Amazon pay their fair share of taxes.

Corbyn, however, has been hammered by constant attacks by Britain's partisan press.

The Mail on Sunday quoted a US rabbi as saying that Corbyn was the most dangerous anti-Semite in the world, referring to long complaints that the Labour Party has not stamped out anti-Semitism in its ranks.

The coverage of Johnson, by contrast, featured a photo of the prime minister with his new dog.

Steven Barnett, a communications professor with the University of Westminster, said a chronic anti-Corbyn mood in most British national newspapers has made it much harder for the Labour leader to get his basic message out to voters.

"In terms of mainstream media, what you've got is an extremely biased and quite visceral campaign being waged against Jeremy Corbyn," he said. "I'm not a Corbyn supporter but I would say he has not had a fair crack of the whip."

Tim Bale, a politics professor at Queen Mary University in London, says Corbyn is not expanding his appeal.

"Polling suggests that he's the most unpopular opposition leader that we've ever seen since polling began on leaders of the opposition back in the 1970s," Bale said.

"He's seen as weak. He's seen as indecisive. He's seen as unpatriotic. He's seen as soft on terrorism and crime. And he's seen as someone who simply can't make up their mind on Brexit."

Corbyn has also been hurt by the very vocal rejection of his views by prominent members of the Jewish community.

First the Jewish Chronicle newspaper warned that many Jews were considering leaving Britain if Corbyn wins, then the country's chief rabbi - who usually shies away from politics - warned that Corbyn was unfit for office.

The Labour leader is a longtime supporter of Palestinian causes who has been highly critical of Israel's government, but critics say he goes beyond that and tolerates party members who make anti-Semitic statements.

Corbyn's other Achilles heel is Brexit, Britain's impending departure from the European Union, now scheduled to take place on January 31.

Corbyn has crafted a Brexit policy designed to keep Labour seats in areas that backed Brexit in the 2016 referendum. It's a cautious approach in which he promises to negotiate a new divorce deal with Europe and then hold a second referendum on whether to endorse that deal or remain in the EU.

He says as prime minister he would be neutral in a second referendum, letting the people decide and then implementing that decision.

That has given Johnson his most prominent attack line, repeated literally hundreds of times on the trail: the assertion that Corbyn refuses to take a stand on the most important matter of the day for his country.

Australian Associated Press