Four months after his Brexiter brother Boris quit as foreign secretary, the remainer MP for Orpington and rail minister said he could not vote for the deal, which May is expected to bring back to parliament within weeks, and instead would throw his weight behind a second referendum.
Show Hide Jo Johnson MP: the less well-known younger brother When Jo Johnson made his maiden speech in the House of Commons, shortly after his election in 2010, he was keen to highlight the differences with his better known, older brother.
Anyone hoping that I will enliven proceedings in the manner of one of my elder brothers, the former member for Henley, is likely to be disappointed, the newly elected MP said, before giving a short political history of his constituency, Orpington in Kent.
Yet, humour apart, the similarities between Boris and Jo are far greater than the differences. Both were educated at Eton and Balliol College, Oxford, although Jo, seven-and-a-half-years younger, outshone Boris with a first in modern history.
Jo Johnson also pursued a career in journalism before entering politics, after a short stint at Deutsche Bank. He worked at the Financial Times for 13 years, where he edited the Lex investment column after stints abroad in Paris and New Delhi.
Jo Johnson warns people Kent of no deal Brexit as he quits ministerial role
The 46-year-old was selected for the safe Conservative seat of Orpington by the narrowest of margins, beating Sajid Javid, after the first ballot between the two was tied. He won by a single vote among association members on the second ballot.
A ministerial career looked likely and Johnson became the first in his family to get a job at No 10 when he was made head of the Downing Street policy unit by David Cameron in 2013 although, at the time, there was some surprise not because of his talents but because of his relative leftwing views.
Some colleagues even described him as pro European but he compiled the 2015 manifesto on behalf of Cameron, which included the fateful promise to hold an in/out referendum on the UKs membership of the EU.
Kent County Council insists the government is listening to its concerns but the former transport minister suggests that ministers continue to grapple with a challenge to ensure frictionless trade and smooth Customs arrangement after next March.
Johnson subsequently became universities minister after the 2015 election, a job he enjoyed and in which he tried to wrestle with the problem of growing student debt, before, to his disappointment, he was reshuffled to become rail minister.
In his resignation statement Johnson warned that Theresa Mays Brexit plans would leave the UK vassalage and chaos. If his career as an MP began with a promise that he would sound different to his brother, with his latest criticisms of the prime minister he sounds dangerously similar.
Thank you for your feedback. It has become increasingly clear to me that the withdrawal agreement, which is being finalised in Brussels and Whitehall even as I write, will be a terrible mistake, he wrote in an online article.
He said the public were being offered an agreement that will leave our country economically weakened, with no say in the EU rules it must follow and years of uncertainty for business or a no-deal Brexit that I know as a transport minister will inflict untold damage on our nation.
To present the nation with a choice between two deeply unattractive outcomes, vassalage and chaos, is a failure of British statecraft on a scale unseen since the Suez crisis.
The pound fell on the foreign exchanges after Johnsons resignation, sliding by almost 0.7% against the dollar to drop below $1.30 (£1).
Johnson said the mooted deal had united him in fraternal dismay with Boris, who stepped down as foreign secretary in July, saying he could not support Mays Chequers strategy.
My brother Boris, who led the leave campaign, is as unhappy with the governments proposals as I am. Indeed he recently observed that the proposed arrangements were substantially worse than staying in the EU. On that he is unquestionably right, he said.
The former foreign secretary tweeted his boundless admiration for his brother, saying: We may not have agreed about Brexit but we are united in dismay at the intellectually and politically indefensible … UK position.
As Johnson added his voice to the small but growing list of Conservatives calling for the public to be given a say on Brexit, Labour leader Jeremy Corbyn told German newspaper Der Spiegel: We cant stop it. The referendum took place. Article 50 has been triggered. What we can do is recognise the reasons why people voted leave.
Bilimoria, who has built Cobra into a household name, said the Brexit process was like watching a train crash in slow motion. People are now waking up and seeing that this emperor has no clothes. Its happening day by day.
Corbyn and his frontbench colleagues have consistently said they will respect the result of the 2016 referendum, fearing that leave voters in Labour constituencies would reject the party if it swings its weight behind blocking Brexit.
He said: Business leaders whingeing about uncertainty are the same people calling for a second vote, which would take a year, make us look ridiculous as a nation and thus add hugely to even more global uncertainty.
Sterling tumbles after Jo Johnson resignation
Corbyn also rehearsed some of his reservations about the EU, saying: Ive been critical of the competitions policy in Europe and the move towards free market, and obviously critical in the past of their treatment of Greece, although that was mostly the eurozone that did that. My idea is of a social Europe with inclusive societies that work for everyone and not just for a few.
Will Jo Johnsons exit shift Brexit balance?
Johnsons shock resignation came just hours after Mays de facto deputy, David Lidington, said he remained confident that the government could win MPs backing for the deal.
Lidington has insisted the government remains confident it can get its Brexit deal through parliament, despite the Democratic Unionist party (DUP) warning it was prepared to vote it down.
Jo Johnson voted to remain in the EU while his brother Boris, who quit as foreign secretary in July, was a leading Brexiteer.
Read more Speaking in the Isle of Man, where he was attending a meeting of the British-Irish Council, Lidington said he believed a new dynamic would emerge once MPs saw the full text of the proposed agreement. He said: I hope and I believe that we can secure that majority in parliament.
Johnsons statement was published after May spent much of the day in France and Belgium, laying wreaths alongside fellow leaders to mark the centenary of the Armistice.
Transport minister Jo Johnson QUITS warning that Brexit is a disaster
Downing Street responded with a terse statement. A spokesman said: The referendum in 2016 was the biggest democratic exercise in this countrys history. We will not under any circumstances have a second referendum. The PM thanks Jo Johnson for his work in government.
As negotiations with Brussels enter their final fraught days, Mays approach to the talks has come under fire from both wings of her warring party, with the pro-Brexit European Research Group and europhiles such as Anna Soubry, fiercely critical of her stance.
Following Johnsons resignation, Soubry said: Jo isnt the only minister who shares these views and I hope others will follow his lead. We are reaching that time when people have to stand up and be counted, because if they dont we are going to sleepwalk to disaster and it doesnt have to be like this.
The DUP, whose 10 MPs May relies on for her majority, has also suggested it could vote down the deal if it fears it could result in new customs or regulatory checks between the UK and Northern Ireland.
Read more In seeking to prevent that outcome, the government is proposing that the UK would effectively enter a temporary customs union with the EU if a trade deal cannot be struck by the end of the transition period in December 2020 to avoid such checks.
Johnson became the latest senior Tory to back the idea of a second referendum and appeared to support the approach suggested by the former education secretary Justine Greening, who has suggested a three-option referendum.
On this most crucial of questions, I believe it is entirely right to go back to the people and ask them to confirm their decision to leave the EU and, if they choose to do that, to give them the final say on whether we leave with the prime ministers deal or without it, Johnson said. To do anything less will do grave damage to our democracy.
His decision was welcomed by campaigners for a second referendum, with some privately suggesting other junior ministers could join him in the coming days.
UK government minister Jo Johnson resigns over Theresa Mays Brexit plan
Eloise Todd, of the anti-Brexit campaign group Best for Britain, said: This is an incredibly brave move from Jo Johnson at a time when the public desperately needs more MPs to act in the national interest. Weve been hurtling towards a blindfolded Brexit for too long, so its about time that politicians hand back control to the people of this country by giving them the final say on Brexit with the option to stay and lead in Europe.
The shadow Brexit minister, Jenny Chapman, said: Jo Johnson is the 18th minister to resign from Theresa Mays government. She has lost all authority and is incapable of negotiating a Brexit deal within her own party, let alone with the EU.