LONDON • Britain's main opposition leader Jeremy Corbyn has apologised to supporters for overseeing his Labour Party's worst election defeat since before World War II.

But the veteran socialist defended his far-left campaign platform and gave no clear indication of when he might step down.

"I will make no bones about it. The election result on Thursday was a body blow for everyone who so desperately needs real change in our country," Mr Corbyn wrote in the Sunday Mirror newspaper.

"I wanted to unite the country that I love but I am sorry that we came up short and I take my responsibility for it."

Mr Corbyn had said last Friday that he would step down at some point early next year. But the century-old party has no clear successor and is being riven by infighting within its senior ranks.

Labour's election campaign was dogged by voter doubts about its vague position on Brexit and allegations of anti-Semitism within the party's senior ranks.

Mr Corbyn tried to shift the campaign's focus to bread-and-butter social issues, traditionally important to Labour voters.

"But despite our best efforts, this election was ultimately about Brexit," he admitted in his letter.

"The Tory campaign, amplified by most of the media, managed to persuade many that only Boris Johnson could 'get Brexit done'," he said in reference to Mr Johnson's campaign slogan to get the country out of the European Union.

"We will learn the lessons of this defeat, above all by listening to those lifelong Labour voters who we have lost in working-class communities."

A process to find a new leader is expected to start early next year. Here are some of the people who could replace him:

PEOPLE WHO COULD REPLACE OPPOSITION LEADER

JOHN MCDONNELL, 68

The follower of Marx has long harboured ambitions to become leader, putting himself forward to stand in 2007 and again in 2010 to challenge prime ministers Tony Blair and Gordon Brown.

Instead, Mr McDonnell became Labour's economy spokesman in 2015 when his old friend, Mr Corbyn, won the leadership bid. Since then, he has gained a reputation as a pragmatic politician with an ability to speak to both sides of the debate, one day taking tea with bankers from Goldman Sachs and the next calling for the overthrow of capitalism.

After deputy leader Tom Watson's resignation, Mr McDonnell appears to be a natural successor though he has ruled himself out of the running. Instead, he may be poised to become a caretaker leader while the party decides how to move forward.

JESS PHILLIPS, 38

Known for her blunt and witty speeches, the MP from Birmingham has already said she may throw her hat into the ring. Despite sharing many of the same left-leaning views as Mr Corbyn, she has been a vocal critic of him, saying he is not capable of winning a majority for Labour and repeatedly threatening to quit the party.

KEIR STARMER, 57

The bookies' favourite, Mr Corbyn's Brexit spokesman has not always been loyal to the current leader - particularly when it comes to the question of Britain's relationship with the EU. Mr Starmer backed Mr Corbyn's rivals in the 2015 and 2016 leadership contests and is one of the party's most vocal remainers.

REBECCA LONG-BAILEY, 40

The young and media-savvy MP hails from a northern constituency with a safe majority. Crucially, she is also loyal to the leadership, even standing in for Mr Corbyn at Prime Minister's Questions.

EMILY THORNBERRY, 59

The shadow foreign secretary is widely expected to toss her hat into the ring, especially after she refused to rule out a leadership bid in a New Statesman magazine interview earlier this month. A strong media performer with experience in Mr Ed Miliband's and Mr Corbyn's senior leadership teams, Ms Thornberry pushed hard for Labour to back holding a second referendum.

ANGELA RAYNER, 39

Ms Rayner has been at the forefront of the party's election campaign, regularly facing the cameras and leading rallies across the country. In her role as shadow education secretary, she spearheaded Labour's National Education Service, which was supposed to do for education what the National Health Service did for health.

AGENCE FRANCE-PRESSE, BLOOMBERG