Politicians vying to replace Jeremy Corbyn as leader of Britain's faltering Labour Party pleaded for unity during their first campaign event held Saturday in Liverpool.

Most of the leading contenders called for senior party figures to stop attacking one another and to focus on coming up with a strategy for challenging Prime Minister Boris Johnson.

Labour, the U.K.'s main opposition party, suffered a disastrous election loss to Johnson's Conservative Party last month.

From left, Labour Members of Parliament, Rebecca Long-Bailey, Jess Phillips, Emily Thornberry, Lisa Nandy and Keir Starmer stand on the stage, during the first Labour leadership hustings at the ACC Liverpool, in Liverpool, England, Saturday, Jan. 18, 2020. (Danny LawsonPA via AP)

From left, Labour Members of Parliament, Rebecca Long-Bailey, Jess Phillips, Emily Thornberry, Lisa Nandy and Keir Starmer stand on the stage, during the first Labour leadership hustings at the ACC Liverpool, in Liverpool, England, Saturday, Jan. 18, 2020. (Danny LawsonPA via AP)

The “name-calling within the party has been horrendous," one of the leadership hopefuls, Jess Phillips, said.

Phillips said Labour must build a “broad team" if it is to rebound quickly from its weakest election performance since 1935.

Phillips also said Labour lost the “moral high ground” by failing to address anti-Semitism in its ranks. She said British Jews had been frightened by the prospect of a Labour triumph.

Britain's Prime Boris Johnson leaves 10 Downing Street to attend the weekly Prime Ministers' Questions session in parliament in London, Wednesday, Jan. 15, 2020. (AP PhotoKirsty Wigglesworth)

Britain's Prime Boris Johnson leaves 10 Downing Street to attend the weekly Prime Ministers' Questions session in parliament in London, Wednesday, Jan. 15, 2020. (AP PhotoKirsty Wigglesworth)

Corbyn plans to step down when the new party leader is announced in April. Among the prominent contenders is Rebecca Long-Bailey, who is considered the closest to Corbyn in terms of left-wing ideology.

Long-Bailey said the vanquished Labour needs to “reunify and rebuild," citing four years of internecine battles in the party.

Labour has not won a national election since Tony Blair's third consecutive victory in 2005.

In this photo issued by the UK Parliament, showing Britain's main opposition Labour Party leader Jeremy Corbyn, left, sitting with lawmaker Rebecca Long-Bailey during the traditional parliamentary session Prime Minister's Questions inside the House of Commons in London Wednesday Jan. 15, 2020. Rebecca Long-Bailey is a contender to become leader of the Labour Party. (Jessica TaylorUK Parliament via AP)

In this photo issued by the UK Parliament, showing Britain's main opposition Labour Party leader Jeremy Corbyn, left, sitting with lawmaker Rebecca Long-Bailey during the traditional parliamentary session Prime Minister's Questions inside the House of Commons in London Wednesday Jan. 15, 2020. Rebecca Long-Bailey is a contender to become leader of the Labour Party. (Jessica TaylorUK Parliament via AP)

The campaign event drew about 500 Labour members seeking a first-hand look at the candidates.