British Prime Minister Boris Johnson’s Conservative Party won 365 of the 650 seats in the House of Commons in Thursday’s landslide election. Labour took 203 seats, its worst total since 1935.

“I’m sorry that we came up short and I take my responsibility for it,” Corbyn wrote in a letter published in the left-leaning Sunday Mirror newspaper.

Corbyn, who has faced fierce criticism from within his own party in the aftermath of the electoral carnage, has said he will step down as Labour leader after a “period of reflection.”

The process of choosing a replacement will begin early next year, but some have called for Corbyn’s immediate resignation.

“I remain proud of the campaign we fought. I’m proud that no matter how low our opponents went, we refused to join them in the gutter,” Corbyn wrote.

“And I’m proud that our message was one of hope, rather than fear.”

Corbyn’s policies failed to energise voters weary of more than three years of political wrangling over Britain’s divorce from the European Union.

Johnson’s campaign, meanwhile, revolved around three words: His pledge to “get Brexit done.” Britain is scheduled to leave the EU on January 31.