Boris Johnson speaks at a Conservative Party leadership campaign hustings at in London recently | Credit | Irish Times

LONDON (Reuters Breaking views) – Boris Johnson has finally realised his ambition. The former mayor of London and prominent Brexiteer is set to become the UK’s next prime minister after winning the contest to lead the Conservative Party, garnering 66% of the roughly 139,000 votes cast by party members.

His triumph will be fleeting, though. To avoid a shorter, even less successful tenure than his predecessor Theresa May, he must wriggle through one of three narrow escape routes.

Johnson campaigned on the promise that Britain will leave the European Union by Oct. 31 – “do or die”.

The least disruptive way to achieve that would be to succeed where May failed: by securing a Brexit deal with the EU that is approved by parliament.

Deal…

The former foreign secretary has dismissed the idea of making a few cosmetic tweaks to the agreement May negotiated last November. Instead, he insists on ditching the Northern Ireland “backstop”.

This requires Britain to stay in a customs union with the EU until it agrees on a trade deal that ensures there will be no border controls between the province and the Republic of Ireland. Johnson’s difficulty with this course is that European leaders have repeatedly ruled out reopening the agreement.

One option would be to keep Britain even more closely aligned to the EU after the official separation while the two sides negotiate their future relationship.

For example, Britain and the EU could agree to keep extending the post-Brexit implementation period until a trade deal is signed. The backstop would no longer be needed. In the meantime, however, Britain would remain an EU member in all but name.

That idea would horrify the eurosceptics who are among Johnson’s most enthusiastic supporters. And he needs their help to secure the 320 votes required to get any revised deal through parliament. The government’s slender majority depends on the support of 10 representatives of the Northern Irish Democratic Unionist Party.

In March, those members, as well as 34 Conservatives, voted against May’s agreement. Neither group is showing any sign of softening their stance. The Conservative leadership contest has hardened attitudes in the party against any deal.

Johnson is largely responsible for that shift. He has rashly promised to force through a “no-deal” Brexit if necessary, regardless of the economic damage.

Here, too, the parliamentary arithmetic remains stacked against him. Moderate Conservative lawmakers, an increasingly vocal minority, have vowed to frustrate such an outcome.

Last week, 17 broke ranks to support a move that makes it harder for Johnson to take the dramatic step of suspending parliament so that a “no-deal” Brexit would happen by default.

Conservatives including Philip Hammond, the outgoing chancellor of the exchequer, have even hinted they would support a motion of no confidence in the government if that was required to prevent “no deal”.

His resistance is based on the costly shock to the UK economy that government forecasters expect would result from leaving the EU’s single market and customs union with no transitional arrangements in place.

Johnson’s parliamentary majority, even with the DUP’s backing, is so small that only a handful of members would need to carry out that threat to bring his administration crashing down.

… Or Redeal?

If parliament is deadlocked, Johnson’s only remaining escape route is to seek a new electoral mandate. Last week, he said calling an election before Britain had left the EU would be “the height of folly”.

Opinion polls suggest he’s right: Only about a quarter of the electorate would currently choose the Conservatives. The opposition Labour Party, led by Jeremy Corbyn, has about the same level of support, while the newly formed Brexit Party and the pro-European Liberal Democrats might each get about a fifth of the vote.

Johnson could join forces with the Brexit Party, but only at the expense of alienating more of his party’s moderate supporters – and committing himself to a “no-deal” Brexit if he won.

An election would, therefore, represent a desperate gamble. In 2017, May tried the same tactic to establish her credibility with British voters after she, too, became prime minister following an internal party contest. It cost the Conservatives their outright parliamentary majority.

Crashing out without a deal, meanwhile, would immediately confront Britons with the realities of life outside the EU.

Far from the “clean break” promised by Brexit supporters, Britain would enter what Ivan Rogers, the UK’s former permanent representative to the EU, describes as “a volatile and uncertain transitional state of purgatory”.

Johnson’s decision to join the Brexit campaign early in 2016 has helped him achieve his ultimate ambition. It may yet speed his downfall.