Theresa May will try to draw a line under weeks of turmoil by telling squabbling cabinet ministers to stop worrying about their own “job security” and focus on the national interest.

Ms May will tell her party she will not “hide from a challenge” and demand that after a lengthy period of soul-searching following the election that ministers “shape up”.

In a series of interviews ahead of her speech Ms May specifically addressed the threat to her premiership from Boris Johnson, brushing aside claims he undermined her and reminding the country that he sits in “my cabinet”.

The Prime Minister had started the conference with her future hanging in the balance in the face of constant media interventions from Mr Johnson that appeared to challenge her authority.

But with other ministers rebuking the Foreign Secretary, a key moment passed on Tuesday when Mr Johnson gave full-throated support to the PM from the conference stage.

In her speech, Ms May will say: “Let us do our duty by Britain. Let us shape up and give the country the government it needs.”

The Prime Minister will go on: “Beyond this hall, beyond the gossip pages of the newspapers, and beyond the streets, corridors and meeting rooms of Westminster, life continues – the daily lives of ordinary working people go on. And they must be our focus today.

“Not worrying about our job security, but theirs. Not addressing our concerns, but the issues, the problems, the challenges, that concern them. Not focusing on our future, but on the future of their children and their grandchildren – doing everything we can to ensure their tomorrow will be better than our today.”

Tory conference 2017 – in pictures Show all 23 1 /23 Tory conference 2017 – in pictures Tory conference 2017 – in pictures Comedian Simon Brodkin hands Theresa May a p45 during her conference speech @simonbrodkin/Twitter screengrab Tory conference 2017 – in pictures Britain's Prime Minister Theresa May struggles with her water after she suffered a coughing fit whilst addressing the Conservative Party conference in Manchester Reuters Tory conference 2017 – in pictures Britain's Foreign Secretary Boris Johnson delivers his speech on the third day of the Conservative Party annual conference Tory conference 2017 – in pictures Bear Grylls at the Conservative party conference at the Manchester Central Convention Complex PA Tory conference 2017 – in pictures Britain's International Development Secretary Priti Patel gestures after delivering her speech on the third day of the Conservative Party conference Paul Ellis/AFP Tory conference 2017 – in pictures Prime Minister Theresa May and Chancellor Philip Hammond visit a home in Manchester during the Conservative Party conference in the city Phil Noble/PA Tory conference 2017 – in pictures Britain's Foreign Secretary Boris Johnson returns from a morning run on the second day of the Conservative Party Conference, in Manchester Reuters/Phil Noble Tory conference 2017 – in pictures Delegates view a display board showing the history of the Conservative Party as they arrive for the first day of the annual Conservative Party conference Getty Tory conference 2017 – in pictures Delegates carry pro-Brexit bags as they arrive for the first day of the annual Conservative Party conference Getty Tory conference 2017 – in pictures Delegates listen to Justine Greening's speech on the first day of conference Carl Court/Getty Tory conference 2017 – in pictures Britain's Prime Minister Theresa May and her husband Philip applaud a speaker on the first day of the annual Conservative Party conference Carl Court/Getty Tory conference 2017 – in pictures Scottish Conservative leader Ruth Davidson speaks at the Conservative Party Conference at the Manchester Central Convention Complex PA Tory conference 2017 – in pictures Secretary of State for Education, Justine Greening, speaks on the first day of the conference Carl Court/Getty Tory conference 2017 – in pictures Chairman of the Conservative Party, Patrick McLoughlin, speaks at the opening of the first day of the Tory party conference Tory conference 2017 – in pictures Chancellor of the Exchequer, Philip Hammond, arrives for the first day of Tory party conference Carl Court/Getty Tory conference 2017 – in pictures Secretary of State for Defence, Michael Fallon, arrives at conference Getty Tory conference 2017 – in pictures Home Secretary, Amber Rudd (C), attends the first day of the Conservative Party conference Carl Court/Getty Tory conference 2017 – in pictures Secretary of State for Communities and Local Government, Sajid Javid, attends the first day of the Conservative Party conference Getty Tory conference 2017 – in pictures Former Conservative minister, Edwina Currie, at the first day of conference Carl Court/Getty Tory conference 2017 – in pictures Secretary of State for International Trade, Liam Fox, arrives at conference Carl Court/Getty Tory conference 2017 – in pictures Britain's Foreign Secretary, Boris Johnson, arrives at the conference hotel for the Conservative Party Conference Reuters/Darren Staples Tory conference 2017 – in pictures The anti-Tory march makes its way to the Conservative party conference in Manchester Peter Byrne/PA Tory conference 2017 – in pictures A demonstrator walks a dog wearing a European Union flag during a protest on the opening day of the Conservative Party Conference, in Manchester Reuters/Darren Staples

At the start of the conference Ms May was forced to apologise to a private meeting of party members for the seats lost at the election.

But the tone Ms May will set on Wednesday will be tougher and more forward-looking. She will say: “None of this will be easy. There will be obstacles and barriers along the way.

“But it has never been my style to hide from a challenge, to shrink from a task, to retreat in the face of difficulty, to give up and turn away.

“And it is when tested the most that we reach deep within ourselves and find that our capacity to rise to the challenge before us may well be limitless.”

In his much-anticipated speech on Tuesday Mr Johnson said “the whole country owes [Ms May] a debt for her steadfastness” and insisted she would deliver a good Brexit deal.

But the about-turn comes after he published a 4,000 word article and gave a wide-ranging interview at the start of the week in which he went well beyond his own brief and appeared to go further than Ms May’s approach to Brexit.

Asked in a BBC interview whether Mr Johnson’s interventions had undermined her, the Tory leader said: “It doesn't undermine what I am doing at all.”

When questioned as to whether he had leadership skills, she said: “Boris is in my Cabinet as the Foreign Secretary.”

Theresa May claims Jeremy Corbyn 'changed the political consensus'

There had been claims from allies of Mr Johnson that he had pushed the Prime Minister to reduce the proposed length of a Brexit transition period from five years to two years.

But Ms May said: “No, the Florence speech was the result of discussions around Cabinet and, yes, my judgement about what it was necessary to say at this stage in the negotiations.

“The whole Cabinet came together. They agreed that speech. They agreed the position the Government is taking.”

The renewed public unity at the top of the party will be tested quickly with the European Council set to deny the UK an opportunity to move Brexit negotiations on to a future trade deal.