Theresa May’s key aides Nick Timothy and Fiona Hill have resigned, taking the blame for her disastrous election campaign.

Mr Timothy said he was taking responsibility for the social care U-turn which torpedoed her manifesto, acknowledging he had “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,” he added.

A Conservative spokesman quickly announced that Fiona Hill, Ms May’s other joint chief of staff, had also resigned.

The twin departures will ease the pressure on Ms May herself, after a survey showed that majority of Tory members believe she should step down.

Strikingly, Mr Timothy urged Conservative MPs to “unite behind the Prime Minister, and focus on the need to heal the divisions in our country.”

The appeal reflected the growing belief among Tory MPs that Ms May should stay only in the short term, to provide stability and start the Brexit talks, before making way.

Since Friday’s results, some senior Tories are referring to Ms May as an “interim leader” – and her Cabinet has failed to come out publicly to support her.

Ms Hill released only a short statement saying it had been “a pleasure to work with such an excellent Prime Minister”.

“I have no doubt at all that Theresa May will continue to serve and work hard as Prime Minister – and do it brilliantly,” Ms Hill added.

The resignations came just hours after another former Downing Street aide revealed how she oversaw a “toxic” operation at No 10 and relied on Ms Hill’s “crazy ideas”.

Katie Perrior lifted the lid on a “dysfunctional” operation, which saw Cabinet ministers bombarded with rude text messages by the twin chiefs of staff.

Although the departures of Mr Timothy and Ms Hill will buy the Prime Minister breathing space, they are also a huge personal blow to her.

The pair worked with Ms May through her time as Home Secretary and were seen as crucial to her project to re-make the Tory party.

Meanwhile, it would require 15 per cent of Conservative MPs – a total of 48 – to write to Graham Brady, the chairman of the backbench 1922 Committee, to trigger a vote of no-confidence in her leadership.

In his statement, Mr Timothy revealed he resigned yesterday, although there was no announcement – and accepted seven years of spending cuts also helped explain the Tory setback.

“Britain is a divided country: many are tired of austerity, many remain frustrated or angry about Brexit, and many younger people feel they lack the opportunities enjoyed by their parents’ generation,” he said.

However, Mr Timothy insisted Ms May was “the one political leader who understands this division, and who has been working to address it.”

Intriguingly, he said the Conservatives had failed to detect Labour’s surge, because “we were not talking to the people who decided to vote for Labour”.

And he sounded a warning to wavering Tory MPs, saying: “The Brexit negotiations are due to begin, and if the United Kingdom is to get the right deal, there is no time to waste.