Europe’s Fragile Center Takes New Blows

ROME—Europe’s months of electoral showdowns between mainstream and populist parties have ended with the establishment weakened in Germany and defeated in Italy—and trouble brewing for both countries.

A new bipartisan governing pact sealed Sunday in Germany could further fuel voter discontent with longtime incumbents in the European Union’s most important country, potentially sapping Chancellor Angela Merkel’s authority in what is expected to be her final term.