Chancellor Angela Merkel’s opponents are assailing her credibility after her finance minister said Greece will need a third bailout package — injecting Europe’s debt crisis for the first time into the campaign for next month’s German elections. Germany, Europe’s biggest economy, has been a central player in the crisis. It’s the biggest contributor to bailouts of struggling countries and has led an austerity-heavy response that is often criticized abroad. But with Germans largely insulated by their own healthy economy and low unemployment, there’s been little incentive for anyone to make Europe a big issue in the country’s September 22 elections. Finance Minister Wolfgang Schaeuble said that “there will have to be a program for Greece once again.” That was a small but significant departure from previous assertions that more help is likely — but not inevitable — once Greece’s current bailout expires next year.