British Cabinet Minister David Frost, who led Brexit negotiations under Prime Minister Boris Johnson, has resigned from government, The Mail on reported on Sunday.

The newspaper said Frost would step down in January due to “disillusionment” with the direction of government policy, citing a high-level government source.

Johnson’s office did not immediately respond when contacted by AFP about the reported loss of a trusted ally, which would deal another blow to the besieged leader.

The weekly reported online that Frost handed in his resignation a week ago, but was persuaded to stay until New Years.

An anonymous source told the newspaper that Frost was opposed to the government’s new restrictions on coronaviruses, focusing on net zero climate targets and tax increases.

Johnson is already reeling from a rebellion of 100 of his MPs in a parliamentary vote on coronavirus measures and the staggering loss of a majority seat of 23,000 in a by-election.

This was in part blamed on a slew of reports that his staff and assistants threw parties this past Christmas despite virus restrictions in place at the time.

The deputy leader of the main opposition Labor party, Angela Rayner, said the resignation showed “a government in utter chaos as the country faces a few uncertain weeks”.

“@BorisJohnson is not up to the task. We deserve better than this buffoonery, ”she tweeted.

Little Liberal Democrat Foreign Affairs spokeswoman Layla Moran said: “This shocking resignation is a sign of the chaos and confusion at the heart of this Conservative government.

“Rats flee Boris Johnson’s sinking ship as it teetering from crisis to crisis. Even once-staunch supporters of the Prime Minister are now abandoning him. ”

And Arlene Foster, who resigned as Prime Minister of Northern Ireland due to post-Brexit trade deals in the British province, said it had huge implications.

“Lord Frost’s resignation from Cabinet is a big moment for the government but a huge one for those of us who thought he would measure up to NI,” she wrote on Twitter.

Frost has been in discussions for weeks over the so-called Northern Ireland Protocol, which governs trade between mainland England, Scotland and Wales and Northern Ireland, and with the European Union. .

London wants the deal it signed last year rescinded, saying it is not working. But Brussels is against it.

Johnson’s Conservative byelection defeat has heightened speculation about a leadership challenge, with Frost potentially considering a tilt to the top post.