(CN) — The United Kingdom, already rattled by Brexit and tensions with Iran, enters a new and unsettling crisis point this week with the pending ascendancy of former London Mayor Boris Johnson, the man likely to take over No. 10 Downing Street and become the leader of the world's fifth-largest economy and one of its strongest militaries.
On Monday, the Conservative Party's grassroots membership cast the final votes in a leadership contest that pits Johnson, a controversial and bombastic pro-Brexit and pro-Trump politician, against Jeremy Hunt, Britain's moderate foreign secretary who's the favorite among Tories keen to see the U.K. maintain close ties with the European Union.
The results of the Tory leadership election are to be announced Tuesday. Johnson is viewed as the clear frontrunner to replace outgoing Prime Minister Theresa May. If he wins, he would take over as prime minister on Wednesday.
His expected victory prompted key members of May's Conservative government to announce they will resign under a Johnson premiership. The resignations pose an immediate challenge to Johnson.
The first to go Monday was Alan Duncan, the foreign office minister. In a resignation letter, Duncan lamented Britain's decision to leave the EU. He previously called Johnson incompetent.
“It is tragic that just when we could have been the dominant intellectual and political force throughout Europe, and beyond, we have had to spend every day working beneath the dark cloud of Brexit,” Duncan wrote.
Duncan was among many senior Tory leaders who voted to Remain in the EU during the 2016 Brexit referendum. But the Leave side — led by Johnson — won by collecting 52% of the votes, most of them cast in England. A majority of voters in Scotland and Northern Ireland voted to remain in the EU.
Besides Duncan, Chancellor of the Exchequer Philip Hammond has said he will step down if Johnson wins. Justice Secretary David Gauke is also set to join his colleagues and resign.
These Cabinet members, like many other moderates in the Tory party, are ardent opponents of Johnson's plan to leave the EU on acrimonious no-deal terms. These moderates worry that leaving the EU without a deal establishing trade and political parameters will cause lasting economic and political damage.
On Monday, two former Labour prime ministers and one former Conservative prime minister also spoke out against leaving without a deal.
“As the evidence mounts of the probable economic and social damage of a 'no-deal' Brexit – and of the rising opposition to it – the new prime minister must choose whether to be the spokesman for an ultra-Brexit faction, or the servant of the nation he leads,” said John Major, a former Tory prime minister. “He cannot be both, and the choice he makes will define his premiership from the moment of its birth.”
At the outset of his campaign for the prime minister's job, Johnson vowed to leave the EU with or without a deal on Oct. 31, a deadline the EU set for Britain to make up its mind about keeping close ties with the EU bloc — as spelled out in a deal May hammered out with the EU — or leave without a deal.