On the eve of May's keynote speech to the Conservative Party Conference in Birmingham, Johnson laid into the proposed Brexit blueprint and said the British public would be unforgiving if the government got it wrong.
But she did her best to appear carefree as she sashayed on to the stage to Abba hit Dancing Queen and joked about the coughing fit and collapsing stage backdrop which marred her calamitous conference speech in Manchester a year ago. "If we cheat the electorate, and Chequers is a cheat, we will escalate that sense of mistrust".
In his speech to the Labour Party conference he said he would vote in favour of her deal if it meant the United Kingdom remained in a customs union and jobs, workers rights and environmental standards were protected. She emphasised it initially in the context of World War I commemoration, remarking that the lesson we ought to learn from that generation is "if we come together there is not limit to what we can achieve - our future is in our hands".
At the conference, May called Brexit a "moment of opportunity" but was forced to urge supporters to get behind her as she heads into what would be the "toughest phase" of negotiations. And last week, I was at the Labour Party conference up in Liverpool. And our message to them must be this: "we get it", May said.
She reasserted her commitment to finding a realistic compromise with the European Union - unlike some of her conservative rivals, who she said "are not acting in the national interest, but their own political interest".
She said the Conservatives next year planned to end austerity implemented in the wake of the 2008 financial crisis.
James Duddridge, the MP for Rochford and Southend, made headlines on Wednesday morning by announcing that he had written a letter to Sir Graham Brady, the chair of the powerful backbench 1922 committee, demanding a vote of no confidence in the prime minister.
Joking about her disastrous speech previous year - when letters fell off the set and she had a coughing fit - Mrs May quipped: 'You'll have to excuse me if I cough - I've been up all night supergluing the backdrop'.
May's rival and Brexit critic, former Foreign Secretary Boris Johnson, shared his vision of a post-Brexit Britain on Tuesday, during a speech in which he said the government should be cutting taxes to stimulate investment.
But Wednesday's speech seemed to have gone down well among the party faithful.
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"The best speech I've ever seen May deliver", said one political writer, while another said: "Best speech of May's premiership".
Johnson, gave a rousing speech at a fringe event at the party's annual conference in which he once again criticized her Brexit proposals.
Admitting that the housing market is "broken", she announced she was lifting the cap on councils borrowing to fund new developments, with the aim of "building the homes this country needs".
"It is no surprise that we have had a range of different views expressed this week", she said.
But I'm realistic and she's not going to say that. And that means two things.
Here we look at who came off best from this week's shindig, who came off worst.
Speculation is growing that London may accept some checks on goods passing between Northern Ireland and the rest of Britain, in place of those on the land border.
In her speech, Mrs May stuck to her plan, called the Chequers proposal after her country residence where she hashed out the proposals in July. Taking back control of our borders, laws and money.
With just six months before Britain is due to exit the European Union, she has so far weathered the Brexit storm, shrugging off a barnstorming speech by her ex-foreign minister Boris Johnson that did little to hide his leadership ambitions. Good for jobs, good for the union.