Theresa May's two closest aides have quit in the wake of the disastrous General Election result.
Mrs May's joint chiefs of staff Nick Timothy and Fiona Hill resigned in the wake of the election which saw Mrs May lose her Commons majority.
The role of Mr Timothy and Ms Hill as Mrs May's joint chiefs of staff had been severely criticised by disgruntled Tories in the wake of the election result.
Mr Timothy acknowledged that one of his regrets was the way Mrs May's social care policy - dubbed the "dementia tax" - by critics had been handled.
The Prime Minister was forced to perform an unprecedented U-turn within days of the publication of the Tory manifesto by announcing that there would be a cap on social care costs, something that had been absent in the original policy document.
In a resignation message on the ConservativeHome website, Mr Timothy said: "I take responsibility for my part in this election campaign, which was the oversight of our policy programme.
"In particular, I regret the decision not to include in the manifesto a ceiling as well as a floor in our proposal to help meet the increasing cost of social care.
"But I would like to make clear that the bizarre media reports about my own role in the policy's inclusion are wrong: it had been the subject of many months of work within Whitehall, and it was not my personal pet project.
"I chose not to rebut these reports as they were published, as to have done so would have been a distraction for the campaign. But I take responsibility for the content of the whole manifesto, which I continue to believe is an honest and strong programme for government."
Meanwhile, Mrs May is seeking to shore up her position in Number 10 by sending her Chief Whip to lead talks with the Democratic Unionist Party.
The Prime Minister has made clear she wants support from her "friends and allies" in the DUP to secure her minority administration ahead of the Queen's Speech on June 19 and has sent Gavin Williamson to Belfast to lead the talks.
A Downing Street spokesman said: "The Chief Whip is in Belfast holding talks with the DUP on how best they can provide support to the Government. We will not be providing a running commentary."