European Commission President Jean-Claude Juncker tells journalists in Brussels on Monday that he felt betrayed by Greek Prime Minister Alexis Tsipras’s surprise call for what amounts to a referendum on Greek departure from the euro. (Virginia Mayo/AP)

He said he felt sorrow and betrayal. He begged, and he blamed.

With Greece’s future in Europe on the line, European Commission President Jean-Claude Juncker pulled off an emotional tour de force Monday as he sought to talk the country down from its perch at the edge of the abyss.

“I very much like the Greeks,” he told reporters gravely during a news conference in Brussels, “and I’d say to them, ‘You should not commit suicide because you are afraid of death.’ ”

The choice now facing Greece may indeed be that dire. But as the dramatic performance by the leader of one of the world’s most hidebound bureaucracies showed, there is also an enormous amount at stake this week for Europe.

Greeks will vote Sunday in a snap referendum that its leftist leader, Prime Minister Alexis Tsipras, has said is meant to give his public the final say on whether he should accept the tough terms of a cash-for-austerity deal from creditors at the European Union, the European Central Bank and the International Monetary Fund. Tsipras wants Greeks to say no, apparently arguing that creditors are bluffing and will not take the catastrophic step of ejecting Greece from the club of 19 nations that use the euro currency.

But across the continent, leaders from Germany to Slovakia, Italy to Portugal, all warned the Greeks that their vote Sunday effectively represents a choice between remaining in the euro zone and not. To let a country reject the rules of the club and stay in it, they seemed to argue, would be more dangerous to the currency union’s future than booting out one recalcitrant member.

“If these principles are no longer adhered to, I am deeply convinced that the euro will fail, and we don't want that,” German Chancellor Angela Merkel said Monday, referring to the need for fiscally sound management.

Merkel, whose nation has lent more to Greece than any other in the European Union, is often seen as the architect of Greek austerity. But some of the countries that are now coming down hardest on Greece are the smaller, poorer euro-zone nations that have accepted the bitter pills of austerity and say the Greeks should, too — though Europe would be fine either way.

Portuguese President Anibal Cavaco Silva, for instance, said Monday that it was an “illusion” that the common currency would be weakened if Greece left. “The euro zone has 19 countries. I hope that Greece will not exit, but, if it does, that still leaves 18,” Silva told reporters in Lisbon, according to the Spanish newswire EFE.

European officials have tried to signal at every turn that the continent is strong enough to weather the consequences of “Grexit,” a Greek departure from the euro zone, and that the fears of a spreading contagion are overblown.

But the truth is no one knows for sure what the broader consequences could be if a union forged over decades on the principle of ever-closer ties suddenly ejects one of its own, leaving it to a potentially catastrophic fate.

“Around the world, there’s a growing incomprehension that the Europeans have allowed something like this to spin out of control,” said Simon Tilford, deputy director of the Center for European Reform. “It could be very damaging to European credibility.”

In the long run, Tilford said, European officials are deluding themselves if they think that other vulnerable economies along Europe’s southern periphery will be protected from a fate similar to Greece’s.

“Once you have the next downturn, which may not be very far away, the consequences of Grexit will become apparent,” he said. “They can control the short-term contagion. But there’s also the longer-term contagion.”

There is also the danger that after decades of convergence, a Greek exit could propel Europe into a period of pulling apart — a development that would have significant economic and geopolitical consequences. Britain, though not in the euro zone, is set to hold a referendum by the end of 2017 on whether to remain part of the European Union.

“So far, the E.U. has been in a continuous process of integration,” said Dušan Reljic, head of the Brussels office of the German Institute for International and Security Affairs. “What we are experiencing now is a huge step toward disintegration. If there was a Grexit, and maybe a Brexit were to follow, the E.U. would have a big problem.”

Greece and Europe have been on a collision course since January, when voters chose the radical leftist Syriza party to take charge in Athens. The party ran on a platform of not only remaking Greece but also abandoning what it sees as a disastrous European fealty to the economics of austerity.

But the heavyweights of Europe haven’t wanted to hand Syriza a victory by giving in to its refusal to enact budget cuts and reforms. Both sides have dug in, and now they are on the brink of a breakup — even though they share the ostensible goal of keeping Greece solvent and inside the euro.

An exit could have implications beyond the economic. Greece has been the first stop for tens of thousands of migrants fleeing conflict in the Middle East and Asia, and a collapse of Greek authority could exacerbate a spiraling crisis for the continent.

The geopolitical consequences, too, could be severe. Russia has actively courted Greece, seeking to exploit its weakness to gain leverage with a NATO member.

But the economic impacts could be most keenly felt. The euro launched in 1999 with the goal of binding the continent after the catastrophic divisions that had marked the previous century. Since then, the currency has added members but has never lost one — a measure of how important it is for European officials to preserve the sense that the union is unbreakable.

And yet, Tilford said, a Greek exit would send an unmistakable signal. “The euro isn’t forever,” he said. “Membership in the currency union is reversible.”

Faiola reported from Paris.

Read more:

Everything you need to know about why Greece might leave the euro

This is what Greece looks like on the brink of economic disaster

Can the European Union recover from Grexit?

Today's coverage from Post correspondents around the world