Theresa May will tell the Conservatives to “shape up” and “go forward together” as she closes her annual party conference on Wednesday.
The PM, who has faced repeated questions about her leadership during the Manchester conference, will vow not to “retreat in the face of difficulty”.
And she will tell colleagues not to worry about their own jobs, but about those of “ordinary working people”.
They must look to “do our duty by Britain”, she will say.
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Having seen her Commons majority vanish after June’s general election and facing calls to sack Foreign Secretary Boris Johnson over his interventions on Brexit, Mrs May has tried to use the conference to unite the party behind her “mission” to transform Britain.
On Tuesday she told the BBC she still had the authority to lead her party and insisted Mr Johnson’s recent comments in newspaper articles had not undermined her.
Mr Johnson praised the PM in his much-anticipated conference speech on Tuesday, in which he also said it was time to “let the British lion roar” and called for Brexit to be a moment of national renewal.
The foreign secretary then faced criticism for remarks about Libya during a fringe event in Manchester.