Jeremy Corbyn and Rebecca Long-Bailey
Jeremy Corbyn and Rebecca Long-BaileyUK Parliament/Jessica Taylor/Handout via REUTERS

The five hopefuls to lead the post-election revival of Britain's battered Labour party on Saturday condemned its struggles with anti-Semitism and vowed to expose the frailties of British Prime Minister Boris Johnson.

Their first joint appearance before Labour members in Liverpool comes with the 120-year-old party reeling from its worst election defeat since 1935.

The successor to veteran socialist Jeremy Corbyn will be charged with fighting Johnson's efforts to reshape Britain's economy after he takes it out of the European Union on January 31.

Finance Minister Sajid Javid gave an early taste Saturday of the disruptions potentially facing UK companies when the Brexit transition period expires at the end of 2020.

"There will not be (economic) alignment. We will not be a rule-taker," Javid said in an interview with the Financial Times. "We will not be in the (European) single market and we will not be in the customs union."

The post-Brexit difficulties some economists predict will test the unity of Johnson's majority in Parliament and give Labour an issue to rally around ahead of the next scheduled election in 2024.

The candidates -- one man and four women -- on stage in Liverpool attempted to launch their leadership bids by confronting anti-Semitism scandals that hounded the party during Corbyn's rule.

"Jewish people were scared of Labour winning the election. That's deeply serious," centrist candidate Jess Phillips said.

Front-runner Kier Starmer said it was "quite possible to be critical of Israeli policies without being anti-Semitic".

"If you are anti-Semitic you shouldn't be in the Labour party, it's as simple as that."

And local MP Lisa Nandy -- a long shot who impressed London pundits in her first round of TV interviews -- said she was "ashamed of where our party ended up."

"We gave the green light to anti-Semites," said Nandy. "Never again do I want to be door knocking with members of the party and be called racist."

Labour's sharp shift to the left during Corbyn's four-year rule saw it sign up in December to what was officially dubbed "the most radical (election platform) in modern times."

The party was also injected with a new wave of members who embraced socialism and rejected the more moderate "New Labour" approach of former Prime Minister Tony Blair.

This new membership ultimately decided to take no stance on Brexit at all -- a position aimed at appeasing both the euroskeptic trade unions and EU-backing voters around London.

Post-election studies showed voters pinning Labour's loss on its indecision over Brexit and seeming inability to confront anti-Semitism.

Some also called promises such as free broadband internet simply too good to be true.

Yet Starmer served as a senior member of Corbyn's shadow cabinet and delivered a keynote address at the party last conference in September.

"Don't trash the last Labour government and don't trash the last four years," he said Saturday.

Second-favorite Rebecca Long-Bailey has been branded a "continuity Corbyn" candidate by the media and is backed by the party's hard left.

She conceded that "we didn't get our messaging right" and "we're not dealing with (anti-Semitism) effectively."

But both she and Starmer called for party unity and castigated the last nine years of Conservative rule.

"You can really see when a government has washed its hands of the people," said Long-Bailey.

Labour's foreign policy spokeswoman Emily Thornberry -- a veteran politician who is seen as a long shot -- said Johnson had a lax grasp of policies and should be "held to account."

"I am a girly swot, I would quote things at him. He would look confused," she said of her debates with Johnson when he was foreign secretary in 2016-2018.

Phillips adopted the same line of attack.

"I have managed to take on Boris Johnson from the back benches and have silenced him," said Phillips. "Johnson would be terrified at facing me."