Anastasia Tregulova celebrates Oktoberfest at a Munich beer hall in the German state of Bavaria. (Matt McClain/The Washington Post)

Like many Bavarians, Rudolf Trunk never had to think very hard about whom to support when it came time to choose leaders of Germany’s southern powerhouse.

The center-right Christian Social Union (CSU) was synonymous with Bavarian identity — lover of lederhosen, pro-industry, devotedly Catholic — and Trunk, a square-jawed business lobbyist, fit right in. 

Not this year. When the party came to this university city framed by cascading vineyards one evening this week to whip up support ahead of crucial elections, Trunk was across town, cheering at a rally for the Greens.

“The CSU has done a lot of wonderful things for Bavaria,” said Trunk, a recent retiree who brought a dash of tweed refinement to a more homespun affair in Würzburg’s central market. “But they tried to be like the far right, and that was the wrong way. I think it’s time for a change after 60 years.” 

It’s a common refrain in Bavaria this October, one that reflects what is widely seen — even by CSU insiders — as a disastrous miscalculation by a once sure-footed party ahead of a Sunday vote for the state’s parliament. 

Faced with an insurgent challenge on its far right from the Alternative for Germany party (AfD), the CSU dramatically broke with its more-moderate sister party, Chancellor Angela Merkel’s Christian Democratic Union, and sought to mimic the newcomer’s hard-line rhetoric on immigration. At several points this year, the rupture nearly collapsed Germany’s national government.

A supporter reads campaign material for Bavarian state premier Markus Söder at a rally in Würzburg on Oct. 9. (Thomas Lohnes/Getty Images)

But the gambit failed to reclaim wayward conservatives, while centrists and liberals who had once backed the big-tent CSU split for more-progressive alternatives, especially the Greens.

The flop illustrates the limits for Europe’s traditional centrist parties of attempting to co-opt the continent’s populist wave. 

In some countries, including the Netherlands and Austria, ­center-right leaders have adopted the far right’s rhetoric and managed to keep or gain power. But their moves have not yielded anything close to a majority, and they have needed partners — the far right, in Austria’s case — in order to govern.

Meanwhile, the shift of establishment parties toward tougher positions on immigration has not stopped the far right’s vote share from continuing to rise continent-wide. And as Bavaria shows, there is peril in abandoning the center ground.

“Voters in the CSU aren’t as far to the right as the people at the top of the party thought they were,” said Christoph Mohamad-Klotzbach, who teaches political science at the University of Würzburg. “And now the left and the center of society are being mobilized against them.”

The consequences for the CSU are likely to be severe. The party has governed Bavaria for 61 straight years, an extraordinary record of political dominance. No one expects that streak to end following Sunday’s vote, when the CSU is widely predicted to come out on top. But victory has rarely looked more like defeat.

Instead of the thumping triumph of previous elections — when the CSU routinely won half or more of all votes — the party is on course to claim just a third this year. A party that has rarely had to share power will need to make a deal with one or more rivals to govern the region. 

Election campaign posters, including for the Christian Social Union and the Greens, hang on display in Tittmoning, Germany. (Sean Gallup/Getty Images)

The humbling of the CSU follows a pattern in Europe of political fragmentation. The party’s Bavarian dynasty is increasingly an anachronism on a continent where political power is rapidly shifting away from the traditionally dominant centrist postwar parties and toward an ever-growing roster of niche movements once relegated to the fringe, either left or right. 

The CSU has long prided itself on being a “people’s party” — a broad-based movement that eschews hard-line ideology or ­single-issue crusades in favor of reasoned compromise and practical solutions. It’s a formula that has worked for generations, keeping everyone from highflying BMW executives to Alpine farmers to Munich shopkeepers happily in the fold. 

It has also, party leaders like to boast, made Bavaria a veritable utopia on earth, with ultralow unemployment, balanced government budgets and negligible crime rates. 

But the 2015 refugee crisis posed a political problem that has vexed the party ever since. When Merkel opened the door to more than a million asylum seekers — and most of them traveled through Bavaria — CSU leader Horst Seehofer vehemently protested. 

Now Germany’s interior minister in addition to being the CSU’s leader, Seehofer has pushed for more-stringent immigration controls this year, and has at times openly defied Merkel. 

The conflict has left the national government paralyzed, lost in internecine feuding. But in his stare-downs with Merkel, Seehofer has been unwilling to make the ultimate break away from the unusual marriage with Merkel’s party, under which the CSU campaigns only in Bavaria, the CDU competes everywhere else and the two form a pact at the federal level.

His strategy has failed to satisfy either side of the polarizing refugee debate.

“Parts of the voter base are saying, ‘Why can’t we do more? We’re such a rich country.’ And then there are those people saying, ‘It can’t continue like this. We need an upper limit. We’re maxed out,’ ” said Oliver Jörg, a CSU member of the Bavarian parliament representing Würzburg. “For us, it’s a challenging experience.”

And some of the inflammatory rhetoric coming from party leaders — especially Seehofer — hasn’t helped, Jörg said.

In March, Seehofer said that “Islam doesn’t belong to Germany” — a point that Merkel quickly refuted. In July, he jovially celebrated the deportation of 69 failed Afghan asylum seekers on his 69th birthday, then deflected blame when one of the men — who had lived in Germany for eight years, since he was a teenager — committed suicide upon arrival in Kabul.

“We don’t need rhetoric like that from our party leader,” Jörg said. 

The party’s other dominant figure, and Seehofer’s chief rival within the CSU, seems to agree.

Bavarian state premier Markus Söder, center, attends a CSU rally in Wurzburg, Germany, on Oct. 9. (Thomas Lohnes/Getty Images)

In an hour-plus speech here before a crowd of around 400 on Tuesday night, Bavarian state premier Markus Söder confined talk of immigration to a few minutes toward the end, and focused instead on pleading with voters to stick with a party that has brought them wealth and security.  

“Some call themselves poor and sexy,” said Söder, jabbing at Germany’s once famously gritty capital, Berlin. “We in Bavaria are strong and stable.”

When he did address immigration, he did so carefully, calling for border controls while thanking those who had volunteered to help refugees and “showed off our best selves.” 

But the softer approach is a relatively new turn for Söder, and calls within the party are already rising for either him or Seehofer — or perhaps both — to step down after the vote. 

As the CSU feuds, other parties have gleefully seized the advantage. 

The AfD barely existed the last time Bavaria voted, in 2013. This time, polls show the party on course to enter the state parliament with about 12 percent of the vote, roughly equal to what it won in the national election last fall.

“The CSU’s strategy is to say to the people, ‘We’re on your side on immigration. You don’t need to vote for the AfD,’” said Richard Graupner, the AfD’s candidate in Schweinfurt, an industrial city north of the more affluent Würzburg. “But people don’t believe it anymore. They know the CSU doesn’t change anything.”

On the other end of the spectrum, the Greens have surged into second place, with a projected 18 percent, by taking voters from both the CSU and the center-left Social Democrats, who have been in free fall nationwide. 

At a small Greens rally in ­Schweinfurt, party leader Annalena Baerbock called for urgent action on climate change to protect melting Alpine glaciers, greater funding to assist abused women and a more humane approach to refugees.

Annalena Baerbock, center, co-leader of the Green Party, attends a campaign event in Schweinfurt, Germany on Oct. 9. (Thomas Lohnes/Getty Images)

The election, she said in an interview after accepting a 12-pack of dark local beer as a thank-you from her hosts, could cement the Green Party’s place at the heart of German politics.

“It’s a turning point,” she said. “Everyone is looking to Bavaria.”

For longtime local activists, that’s astonishing. When volunteers first started putting up Green Party posters in Bavaria decades ago, said Martin Heilig, the region’s conservative voters would eye them warily, “looking to see if you put a bomb there as well.”

But the party has moved on from its radical roots — and Bavaria has changed, too. At the party’s rally in Würzburg, attendees skipped the usual campaign fare of sausages and sauerkraut in favor of vegan falafels dressed in coconut and ginger. 

“If we have a victory, it’s a symbol for all other countries,” said Heilig, the party’s local chair. “We want to be a friendly country, an open Germany. We have the feeling that’s what people want, too.”