National elections take place within a specific global moment. In the 1990s, there was a presumption that we were living in an age of rapid progress. Democracy was spreading. Tyranny was receding. Asia was booming. The European Union was building. Conflict in the Middle East was lessening. The world was cumulatively heading toward greater pluralism, individualism, prosperity and freedom.

Today it’s harder to have faith in rapid progress. Democracy is receding. Autocrats like Vladimir Putin of Russia are marching. The European project is decaying. Economies are struggling. Reactionary forces like the Islamic State and Iran are winning. The Middle East is deteriorating.

In this climate, the tone and focus of politics change. Politics is less about win-win situations and more about zero-sum situations. It is less about reforms that will improve all lives and more about unadorned struggles for power. Who will control the ground in places like Ukraine and Syria? Will Iran get the bomb? Will the White House or Congress grab power over treaties and immigration policy?

At these moments, tough guys do well. Cooperative skills are less valued while confrontational skills are more valued. Benjamin Netanyahu wins re-election in Israel. The pugnacious Nicolas Sarkozy, of all people, is staging a comeback in France. Putin is in his element.

Barack Obama started out as a hope-and-change idealist, but he has had to toughen to fit the times. Angela Merkel is the paradigmatic leader of the age: shrewd, unemotional, nonidealistic, austere and interested in power. As the former U.S. ambassador to Germany John Kornblum told George Packer of The New Yorker: “If you cross her you end up dead. ... There’s a whole list of alpha males who thought they would get her out of the way, and they’re all now in other walks of life.”

In these moments, right-leaning parties tend to do well and have a stronger story to tell on national security. They speak the language of nationalism and cultural cohesion. People who are economically insecure (and more likely to lean left) drop out of the political process.

Both parties, though, change shape to fit the zero-sum contours of the moment. Progressives emphasize compassion less and redistribution more. Conservatives emphasize entrepreneurial dynamism less and the threat of government elites more. Electorates get a little uglier when faith in progress declines. Voters across the spectrum get more cynical and distrustful. They are quicker to perceive threats from The Other.

For example, anti-Semitism is a good barometer of a worsening public mood. According to the Pew Research Center, acts of hostility toward Jews are now rampant in 39 percent of countries, up from 26 percent in 2007. The U.K. Community Security Trust registered 1,168 anti-Semitic incidents in Britain in 2014, more than double the number from the previous year.

It’s rare to have major realignments at a moment like this. Everybody is hunkered down and risk averse. Voters in this battened-down frame of mind are willing to elect familiar faces (better the devil you know). The Israeli, American and European electorates have been remarkably stable over the past decade. In Israel, for example, the overall vote that went to right-wing parties was stable from this election to last; it’s just that the Likud Party grabbed a big share of the nationalist electorate.

Still, you do see some shifts. Extreme parties rise, especially the ones that repel supposed interlopers and oppose elite global projects. We’re seeing that across the globe with the Tea Party, UKIP in Britain, National Front on the right in France and Syriza on the left in Greece.

Extreme parties rarely take power, but they do influence politics because mainstream politicians have to co-opt them. Mainstream politicians have to fight two-front wars: the official one against their ideological opponents and the unofficial one to silence, co-opt and crush the extremists on their own side.

This is what Netanyahu did in Israel. He didn’t literally renounce the idea of a two-state solution forevermore. He just said that it would be too dangerous in the near term as long as Islamist-style radicalism is on the march. (A defensible proposition.) Still, these comments and the ones on Israeli Arabs were blatant panders. He took Knesset seats away from parties to his right by becoming more like them.

These conditions will influence the 2016 American election, too. I’d guess that the cultural moment favors Scott Walker and Chris Christie, who have records of confrontation, over Jeb Bush, who hasn’t won election in this era and has a softer mien. I’d also say they strengthen Hillary Clinton. She has a Merkel-like toughness and may actually benefit from the familiar-face phenomenon.

In general, the power of the cultural moment shapes the candidates. But occasionally there is a leader who can turn a negative popular mood into a positive one. F.D.R. and Reagan did this. But you have to be very, very good.