Predictions of the euro’s demise in the absence of bolder action have grown louder as global growth slows, banking-sector woes compound and governments wobble. The mood was further depressed on Monday when the Group of 7 finance ministers said that they would hold an emergency conference call on Tuesday on the crisis and Portugal announced that it would become the latest European country to fall short of its growth forecast.

As the troubles mount, all sides turn to Germany, the only country with the financial wherewithal to calm the turbulence and guarantee the currency zone’s collective solvency.

“Nothing can be done without German support,” Mr. Soros said.

German officials worry that without safeguards on spending and deficits, the country would quickly be bled dry by overspending partners. To forestall that danger, a proposal by the government’s independent council of economic experts to pool excessive debt has garnered increasing attention.

Under the plan, largely ignored when it was introduced late last year, the debt overhang in the 17 members of the euro currency union — defined as any debt exceeding 60 percent of gross domestic product, or nearly $3 trillion by some estimates — would be transferred into a fund that would be paid off over roughly 25 years. The proposal differs from euro bonds in part because it is limited in scope rather than open-ended, which could help win approval by the German Constitutional Court.

“We have the impression due to conversations with government officials that the government is really examining the pact and the proposals,” said Wolfgang Franz, an economics professor at the University of Mannheim and the chairman of the council. “If I reject euro bonds, if I reject the European Central Bank, we don’t have many measures other than hope.”

Hope has been in increasingly short supply. Mr. Barroso said it was necessary to signal that the euro zone “will do whatever is necessary to assure the stability of our currency. We need to do things faster and we need to go further,” Mr. Barroso said Monday at the news conference. “It is now evident that also for the stability of the euro we need some concrete measures regarding the euro area and the European Union in general.”

What took years to develop could take a surprisingly short time to come crashing down, experts say. The answer from Berlin on euro bonds has never been an absolute “no.” It has always been “not yet.” Only a more integrated euro zone will tap Germany’s good credit, Ms. Merkel has made clear, saying time and again that euro bonds come at the end of that process.