Just hours before Boris Johnson was due to take office as U.K. prime minister, one of the most unconventional architects of Brexit was named as a senior adviser to help implement his pledge to leave the European Union by Oct. 31.

Johnson enters Downing Street at one of the most perilous junctures in post-Second World War British history — the United Kingdom is divided over Brexit and weakened by a three-year political crisis since the Brexit referendum.

His pledge to energize the country and deliver Brexit — do or die — on Oct. 31 sets the United Kingdom up for a showdown with the European Union and thrusts it toward a potential constitutional crisis, or election, at home.

“Like some slumbering giant, we are going to rise and ping off the guy-ropes of self-doubt and negativity,” Johnson, 55, said on Tuesday after he was elected by Conservative Party members.

“We are going to energize the country. We are going to get Brexit done on Oct. 31 and we are going to take advantage of all the opportunities it will bring in a new spirit of can-do.”

To implement Brexit, Johnson will appoint Dominic Cummings, the campaign director of the official Vote Leave campaign, as a senior adviser in Downing Street.

The appointment of Cummings, known for his campaign skills but also for a combative style that challenges the consensus, indicates Johnson is serious about going in hard on Brexit and wants a first-class political campaigner close.

Cummings, who graduated with a top degree from Oxford, says Britain’s political system is broken and Brexit negotiations have been botched by officials and politicians who have thwarted the will of the people.

Political choreography

Wednesday will combine arcane British political choreography with the realpolitik of appointing a new government — likely to be heavy on Brexit supporters.

Prime Minister Theresa May has left Downing Street after a three-year premiership that was mired by crises over Brexit. She will travel to Buckingham Palace to formally tender her resignation to the Queen.

Theresa May leaves 10 Downing Street for her final session in the House of Commons as prime minister in London on Wednesday. Boris Johnson will replace May as U.K. prime minister later Wednesday. (Tim Ireland/Associated Press)

May appeared to be fighting back tears as she was applauded out of the House of Commons chamber. Her finance minister, Philip Hammond, resigned on Wednesday ahead of Johnson’s appointment.

Johnson will then have an audience with the Queen, who will request he form an administration. His formal title will be Prime Minister and First Lord of the Treasury.”

He will enter Downing Street in the afternoon and is expected to give a speech before appointing key members of the government — names that could give a hint of how he will handle Brexit, the U.K.’s most significant decision in decades.

“Boris will build a cabinet showcasing all the talents within the party that truly reflect modern Britain,” a source close to Johnson said.

Brexit government

But Johnson — known for his ambition, mop of blond hair, flowery oratory and a cursory command of detail — must solve a series of riddles if he is to succeed where May failed.

The 2016 Brexit referendum showed a United Kingdom divided about much more than the European Union, and has fuelled soul-searching about everything from secession and immigration to capitalism, empire and modern Britishness.

The pound is weak, the economy is at risk of recession, allies are in despair at the Brexit crisis and foes are testing the the U.K.’s vulnerability.

Johnson is shown with Theresa May while arriving at a NATO meeting in Brussels in 2017 when she was prime minister and he was foreign minister. (Thierry Charlier/The Associated Press)

His party has no majority in Parliament, so the Conservatives only govern with the support of 10 lawmakers from the Brexit-backing Democratic Unionist Party in Northern Ireland.

While Johnson said he does not want an early election, some lawmakers have vowed to thwart any attempt to leave the EU without a divorce deal. Brexit Party Leader Nigel Farage said he was open to an electoral pact with Johnson.

Investors are braced to see who will be handed the top jobs such as finance minister, foreign secretary and Brexit minister.

Interior Minister Sajid Javid is widely tipped to stay in a top job — possibly as finance minister — and was spotted flanking Johnson as he arrived before lawmakers.

There is talk that Johnson will appoint career diplomat David Frost as European Union sherpa and adviser on Europe. 

A record number of ethnic minority politicians are expected to serve as ministers. They include Priti Patel, the former aid minister who resigned in 2017 over undisclosed meetings with Israeli officials, and Employment Minister Alok Sharma.

Foreign Secretary Jeremy Hunt, Johnson’s rival for the leadership, was offered the job of defence minister, but turned it down, Sky reported.

No deal?

If the bloc refuses to negotiate a new Brexit deal by end of October, and Brexit happens regardless, it would send shock waves through the world economy and tip the world’s fifth largest economy into recession or even chaos, investors warn.

Johnson takes part in a tug of war with Armed Forces personnel at the 2015 launch of London Poppy Day during his tenure as mayor of London. (Jonathan Brady/PA via Associated Press)

Brexit without a divorce deal would roil financial markets and, some bankers warn, weaken London’s position as a pre-eminent international financial centre.

Brexit supporters say those fears are overblown and the United Kingdom will thrive if cut loose from the European project, which they cast as a German-dominated bloc that is falling far behind its global competitors such as the United States and China.

“If he really wants a no-deal, he will get it. We will never push an EU member out but we can’t stop him. More likely, his own Parliament would,” one EU diplomat said.

“Johnson has been such a chameleon, he has reinvented himself so many times that it is hard to know what to expect really.”

Another diplomatic source had an ominous warning: “My scenario is purgatory.”