How quickly should Britain divorce from the European Union?

Should Britain’s divorce from the European Union be quick and clean or slow and methodical?

This is the question leaders on the island and continental Europe have started to squabble over following the passage of Britain’s referendum vote Thursday to leave the 28-nation bloc.

The rift among the member nations of the EU shows their different attitudes – and motivations – for how to best move forward with the unprecedented separation. With British Prime Minister David Cameron announcing he will retire by October, and the pound sterling in a freefall, the country’s leaders are treading carefully. German Chancellor Angela Merkel, who will be a lead negotiator of the divorce, is also urging caution. But the EU’s six founding states, already feeling the economic and political aftershocks of “Brexit,” are insisting Britain just get it over with.

“I would like it immediately,” Jean-Claude Juncker, the president of the European commission, told German television. “It is not an amicable divorce, but it was also not an intimate love affair.”

“I do not understand why the British government needs until October to decide whether to send the divorce letter to Brussels,” said Mr. Juncker.  

Because Britain will be the first member nation in the European Union’s 60-year history to leave it, no one is sure how fast to act. Article 50 of the Lisbon Treaty, the bloc’s governing treaty, lays out how member states can withdraw from the union, which starts once Britain invokes the article. The article gives particular focus to how the withdrawal agreement can be negotiated, as well how the withdrawing state’s relationship with the EU can be defined.

But, the rest of the EU has few legal resources to force Britain to start to leave sooner.

“There is no mechanism to compel a state to withdraw from the European Union,” Kenneth Armstrong, a professor of European law at Cambridge University, told The Guardian. “Article 50 is there to allow withdrawal, but no other party has the right to invoke article 50, no other state or institution.”

A member state can be suspended for breaching the EU’s fundamental rights, according to Article 7 of the Lisbon Treaty. It is considered a “nuclear option,” however, and Britain has done nothing to warrant it, said Mr. Armstrong.

“While delay is highly undesirable politically, legally there is nothing that can compel a state to withdraw,” said Armstrong.

It’s clear why the EU’s founding states – Belgium, France, Germany, Italy, Luxembourg and the Netherlands – would like the uncertainty about Britain’s exit resolved sooner, according The New York Times.

“The European Union has other considerable challenges, including the migrant crisis, Greece’s turbulent economy and sanctions on Russia over Ukraine,” writes the Times’s Steven Erlanger and Dan Bilefsky. “European leaders, looking at Spanish elections on Sunday and German and French elections next year, want the uncertainty around the British question resolved as soon as possible so they can try to show their own voters that Brussels is capable and on track.”

The foreign ministers of the union's founding states voiced their feelings of urgency at an emergency meeting Saturday in Berlin to prepare for their meeting with Mr. Cameron Tuesday in Brussels. There, they are expected to ask Cameron to leave the room so they can speak about their plans. French Foreign Minister Jean-Marc Ayrault, when he spoke to The Guardian about Saturday's meeting, said Cameron should step aside now so a new leader can manage the transition.

But Cameron and the rest of Britain are still reeling from the political and economic fallouts of the vote. If Cameron has his way, his successor will be chosen in October at the Conservative party conference, where Article 50 will also be invoked. Boris Johnson, the former mayor of London, one of the leaders of the “Leave” campaign, and a contender to succeed Cameron, echoed the prime minister's cautionary approach. Mr. Johnson said there should be “no haste” in how Britain breaks from the EU, according to The Guardian.

Ms. Merkel approached the disagreement diplomatically Saturday. 

"It should not take ages, that is true, but I would not fight now for a short time frame," she said, according to Reuters. "The negotiations must take place in a businesslike, good climate.”

US Secretary of State John Kerry, who will be the first senior American official to visit the European London and Brussels following the referendum vote, echoed Merkel Sunday, emphasizing thoughtful cooperation.

"The most important thing is that all of us, as leaders, work together to provide as much continuity, as much stability, as much certainty as possible," said Mr. Kerry in Rome, according to the Associated Press.