BERLIN — It has become the buzzword of the summer in Berlin: referendum. The foreign and finance ministers as well as opposition leaders have all come out in favor of allowing Germans to have a direct say in whether to give up more power to European Union institutions.

Although the idea of a referendum is for the moment more notional than concrete, it is gaining currency in Germany’s political debate. Approving it would amount to the exceptional step of a national vote to change the Constitution to allow Germans to relinquish some executive authority to Brussels.

Proponents say that if such a referendum were approved, it would send a strong signal of Germany’s commitment to the euro. It would also streamline the steps needed to save the common European currency, they argue, and appease mounting complaints by Germans that even as they are being asked to pay more to bolster or bail out their troubled euro zone partners, they have no say in where their taxes are flowing or how they are being spent.

Such a referendum comes with the built-in risk that Germans could vote against Europe, with potentially damning consequences for the common currency and the future of the European Union.