FRANKFURT — Under growing pressure to fix bank problems, European officials took a step on Tuesday toward surrendering a cherished national prerogative by proposing to shift banking regulation to a central authority.

The European Commission’s plan could spread the cost of bank rescues and demonstrate that governments are willing to cede power to the strong, centralized institutions many economists say are needed to stabilize the currency union.

Pressure for bold action by Germany’s chancellor, Angela Merkel, and other eurozone leaders escalated Tuesday after a conference call of finance ministers and central bankers from the Group of 7 nations, which include Germany, Japan, and the United States.

While participants said little about the conversation afterward, it is likely that European leaders were urged to move more forcefully to quell a banking crisis in Spain and to keep Greece from leaving the eurozone.

“There’s no question that markets remain skeptical that the measures taken thus far are sufficient to secure the recovery in Europe and remove the risk that the crisis will deepen,’’ Jay Carney, the White House press secretary, said Monday.

The European Commission’s proposal is designed to avoid situations like the one in Spain, where the ills of one institution, Bankia, threaten to destroy what little credibility the government has left with financial markets.

But the plan would not do much to help banks in Spain and Portugal that require immediate aid. The proposals would require formal approval from European governments and the European Parliament, and one of the most important measures would not be expected to go into force until 2018.

In that sense, the move is yet another example of the bloc’s inability to keep up with the fast-moving pressures created by the crisis that began in Greece and is now threatening Spain.

Doubts about Spain deepened Tuesday after the treasury minister, Cristobal Montoro, suggested the government’s borrowing costs were rising to levels that might eventually cut the country off from debt markets.

Montoro said Spain needed help from European institutions to recapitalize, though he did not give an indication of how much money was required.

Spain is planning a bond auction Thursday that could help decide whether the country must seek a full bailout.

The detailed proposal for steps toward a so-called banking union came a day after Germany indicated it might provide greater support for its most indebted eurozone partners in exchange for more centralized control over government spending in Europe.

“The world wants to know how we expect the political union to complement the currency union,’’ Merkel said late Monday.