European democracies have taken a different path.

Parliamentary elections, often in conjunction with proportional representation, have allowed multiple parties — at both ends of the political spectrum — to flourish. In many cases, the European system has empowered anti-immigrant populist parties on the right. These parties have adopted a strategy that might seem strange on its face but actually makes sense, according to the logic of their grievances: exclusionary nationalism combined with generous support for safety-net programs available only to legal residents.

Here and abroad, there are striking similarities in the dynamic that is forcing major adjustments in the political system.

The working class on both sides of the Atlantic is struggling to adapt. “The separation, if not alienation, of the ‘working class’ from the traditional center-left parties” is a “global phenomenon shared by all post-industrial democracies,” Herbert Kitschelt, a professor of international relations at Duke, wrote in an email to me.

The traditional European social democratic left and the Democratic Party are both struggling to address the often conflicting interests of a socially liberal elite and an economically pressed lower class.

Olaf Cramme, a senior adviser to the Cabinet Office in the U.K., and Patrick Diamond, who was an adviser to the Labour government under Tony Blair, published an essay in the Guardian in 2012, “Is Europe’s Left Ready to Govern?” that describes the quandary of once powerful social democratic parties:

Left-of-center parties have been increasingly hampered by cultural cleavages relating to increasing ethnic heterogeneity, the free movement of labour and open migration systems, the rise of new forms of politicized and assertive religious radicalism, and an apparent conflict between “cosmopolitan” and “communitarian” interests. The identities and solidarities on which social democracy in Europe has been built are under increasing strain. New actors on the far left and far right, as well as astutely positioned conservative and Christian democratic parties, will not hesitate to capitalize on the struggle to craft a clear narrative – however myopic and divisive.

Cramme and Diamond then ask:

Are social democrats capable of developing a governing strategy that can live up to these enormous challenges? Although the nation-state has become the principal bastion in the fight against the financial and economic crisis, its “golden age” is irrefutably drawing to a close.

Kitschelt points out that over the past 40 years, multiple parties have emerged in Europe to fill the vacuum. The result is that voters can choose candidates from as many as eight parties. The most powerful insurgents are parties on the radical right, which have been propelled in large part by opposition to immigration.