Mr. Salvini recently announced an alliance of populist, far-right, anti-immigration, euroskeptic parties called “Toward a Europe of Common Sense.” But if he hopes such a coalition can become the largest bloc in the Parliament, the prospects are dim, partly because of a clash of egos and agendas among different populist parties. At the founding event for his alliance, Mr. Salvini produced only three other parties as partners — the Danish People’s Party, the Alternative for Germany and the Finns party, which just came in second in Finland’s national elections, with some 17.5 percent of the vote.
Opinion polls suggest that populist parties could win up to 180 seats in European Parliament, enough to create serious delays and difficulties in the next Parliament, in which the center-right and center-left are expected to lose their traditional majority. Ms. Schaake, the Dutch legislator, said that “the real story is fragmentation and what will happen in the center.” The populists will not agree on everything, she said.
“But they can make a mess.”
In addition to passing or rejecting laws, European lawmakers have new powers that could allow populists to block trade deals, approve the bloc’s budget and play an important role in determining who will replace the European Union’s most powerful leaders: Jean-Claude Juncker, the current president of the European Commission; Donald Tusk, the president of the European Council; and Mario Draghi, head of the European Central Bank.
Even if they are replaced by others from the pro-European mainstream, countries led by euroskeptics, like Italy, Hungary and Poland, will get to nominate powerful commissioners, which could mean more squabbling at the top and a shift away from federalism.
The potential for polarization will reach into the Commission, too, said Daniela Schwarzer, director of the German Council on Foreign Relations. “Who will Orban and Salvini send as commissioners?” she asked. “And the scrutiny of candidates by Parliament will be tougher.” Parliament has the right to scrutinize commissioners and to endorse or reject the whole slate.
Voters, meanwhile, are unpredictable. Turnout is usually low in European races, which gives advantages to motivated, more narrowly focused populist parties. A study of the electorate by the European Council on Foreign Relations found Europe’s voters more volatile than polarized. Immigration, the main topic for many populists, ranked only third among European voter concerns, behind Islamic radicalism, much of it homegrown, and the national economy.
“Swathes of voters,” said Mark Leonard, the council’s director, “are moving fluidly between parties of the right and left.”