Germany is resisting a growing chorus of calls from ailing euro zone members for new help digging out of the debt crisis. The euro zone's economic powerhouse held firm Thursday to its refusal to underwrite debt or guarantee deposits, and it remained on the defensive as more European leaders resist its drumbeat of insistence on austerity. "Germany's strength is not infinite," Chancellor Angela Merkel told the Bundestag on Thursday, stressing that the country couldn't be expected to shoulder the burdens of the euro zone. Her refusal came as Moody's slashed Spain's credit rating by three points to just one notch above junk status, despite the $100 billion E.U. bailout Spain secured last week, and as Italian borrowing costs skyrocketed, too.