The head of Spain's biggest bank has made an impassioned plea for Europe to adopt a so-called union of its euro zone banks as an "essential" route out of the region's crisis.
Writing in the Financial Times, Emilio Botín, the 78-year-old chairman of Santander who routinely keeps a low profile, says: "Banking union is an ambitious, complex and difficult process … but we cannot afford to postpone it."
Banking union, hailed by EU leaders in June as an important antidote to the eurozone crisis, would involve pooling supervision of the region's banks and creating a pan-eurozone safety net to support them.
Policy makers believe that the idea, if implemented promptly and effectively, should break the downward spiral created when weak states underwrite weak banks.
However, it has run into resistance, particularly from Germany, over concerns about how power should be ceded to a single euro area bank supervisor and the risks of about strong states' banks writing guarantees for bank deposits in weak countries.
Mr Botín's intervention comes amid ongoing investors nervousness about banks in peripheral euro zone countries and an intensification of austerity protests across Europe. Spain and Portugal witnessed the most disruption on Wednesday, with a general strike that closed schools and brought transport systems to a halt.
Altogether, 40 unions in 23 countries were due to take part in a "day of action and solidarity", the European Trade Union Confederation said in advance of the action.
Mr Botín does not refer to Spanish austerity, or the backlash against it, in his opinion piece. But he warns that the continent as a whole is at risk if policy makers do not act more decisively. "Europe has been the cornerstone of western society," he writes, "but if we do not act with speed and determination, we run the risk of being swept into decline and irrelevance."
The intervention by Santander and its chairman will be seen as a move to come to the aid of a troubled Spanish government as it battles to implement austerity measures on the one hand and to convince its fellow euro zone countries that it should be able to tap a promised 100 billion euro facility to recapitalize its banks.
Some frustrated EU officials suspect that the political deadlock over supervision is partly an attempt by the euro zone creditor countries to delay any request for EU funds to be injected directly into Spanish banks – a request that can only be made once a common supervision system is established.
Germany is one of the most vocal about its concerns, insisting that the European Central Bank concentrate on big banks and leave small lenders mainly to national authorities – a position that is unacceptable to France, which wants all banks to be covered. A Berlin-led bloc of countries is also warning against rushing the reforms.
Analysts at Barclays warned in a recent note to clients that the prospective change of regulator from Spanish domestic to ECB could be costly, because benign calculations of the group's domestic capital requirements by the Bank of Spain might be ripped up. "With the potential for lead regulation to be passed to the ECB in 2013 ... that [benign view] could change," the analysts wrote.
Mr Botín also insists that a single pan-euro zone deposit guarantee mechanism is "essential to restore confidence".
Establishing a common backstop for the 5 trillion euros of deposits in the euro zone has proved particularly contentious with Germany. Mario Draghi, the ECB president, last week argued that European banks should be spared from being forced to pool their deposit guarantee schemes.