Brexit minister Lord Frost has resigned from the Cabinet, the Mail on Sunday has reported.
Lord Frost, who has led negotiations with the EU, is reported to have handed in his resignation letter to Boris Johnson last week.
But the Mail on Sunday reported he had been convinced to stay on until January.
The newspaper reported it was the introduction of Plan B coronavirus measures that prompted Lord Frost’s decision, including the implementation of Covid passes.
It also said that he had become disillusioned by tax rises and the cost of net zero policies.
Lord Frost has recently been locked in tense rounds of talks with European Commission vice-president Maros Sefcovic as the UK and the EU attempt to close gaps in post-Brexit arrangements.
Labour’s deputy leader Angela Rayner said the news represented “a Government in total chaos right when the country faces an uncertain few weeks”.
She tweeted: “@BorisJohnson isn’t up to the job. We deserve better than this buffoonery.”
Liberal Democrat foreign affairs spokesperson Layla Moran said: “This shock resignation is a sign of the chaos and confusion at the heart of this Conservative government.
“The rats are fleeing Boris Johnson’s sinking ship as he lurches from crisis to crisis.
“Even the Prime Minister’s once-loyal supporters are now abandoning him, just as lifelong Conservative voters are switching in their droves to the Liberal Democrats.
“At a time we need strong leadership to get us through the pandemic, we instead have a weak Prime Minister who has lost the support of his allies and the trust of the British people.”
Northern Ireland’s former first minister Arlene Foster described Lord Frost’s resignation as “enormous”.
In a tweet, she said: “The resignation of Lord Frost from the Cabinet is a big moment for the Government but enormous for those of us who believed he would deliver for NI.”