Merkel, already the largest contributor to the EU's rescue fund, must walk "a very thin line" as she tries to balance her pledge to do whatever is needed to save the euro with voter hostility to the bailouts, said Carsten Brzeski, an economist at ING Groep NV in Brussels. She also risks harming her country's banks by her insistence that bondholders take losses on future bailouts. German lenders hold more than 112 billion euros of debt issued by the governments of Greece, Ireland, Portugal, Spain and Italy, according to data compiled by Bloomberg.