German voters go to the polls today but it is a different world from when the campaign began only a few weeks ago.

Nearly 60 million ­people are choosing a government that will have to grapple with the breakdown of the transatlantic alliance under Donald Trump and new threats to European security just as the country’s vaunted economic model is hitting the skids.

If the polls are correct, the man leading that administration will be conservative opposition chief Fried­rich Merz, a corporate lawyer with a decades-long desire to be chancellor despite never ­serving in government. His in-tray will be staggering. “The big expectations ­mirror the big challenges he’ll face from day one of his likely chancellor­ship,” news weekly Der Spiegel said. “An ­aggressive Russia, a hostile America and a Europe that is drifting apart: Merz could be tested more strongly […] than any ­chancellor of the postwar republic.”

Merz recently admitted that Trump’s effective abandonment of European defence pledges and his vice-president JD Vance’s aggressive backing of the far-right Alternative für Deutschland (AfD) heralded ­“tectonic shifts in the political and economic power centres of the world”. Germany, he said, would not emerge unscathed.

Trump’s undermining of Nato and betrayal of Ukraine are “a wrenching punch to the gut”, said Ursula Münch, director of the Academy for Political Education thinktank in Bavaria, particularly for Merz’s Christian Democratic Union (CDU), which has “solidarity and friendship with the US deep in its DNA”. “The ­biggest ­challenge [for Ger­many] will be ­mustering a united show of strength by the EU and the UK.”

Germany, the world’s third largest economic power and most populous EU country, was already struggling with the muddled legacy of Angela Merkel, one of Merz’s predecessors as CDU leader and his longtime nemesis.

Her 16-year tenure as ­chancellor was marked by reliance on cheap Russian gas, brisk trade with China and Washington’s military and ­intelligence might, allowing Germany to focus on what it did best: manufacturing cars and machine tools while holding the EU together.

Merkel’s successor, Olaf Scholz, took office in December 2021 buoyed by hopes for a fresh approach to long-neglected problems with a technocratic “traffic light” coalition named for the party colours of his centre-left Social Democrats, the pro-business Free Democrats and the ecologist Greens. But only weeks later, Russia’s full-scale invasion of Ukraine blew the best-laid plans of Scholz’s “coalition for progress” permanently off course.

Within days of the war’s outbreak, Scholz declared a Zeitenwende (turning point), establishing a €100bn (£85bn) fund to beef up Germany’s paltry military equipment stocks and pledging to meet a Nato commitment of defence spending at 2% of GDP. By 2024, he had kept that promise.

But the halt of Russian energy supplies sent prices soaring, ­spurring galloping post-pandemic inflation and weighing heavily on industries such as steel and chemicals. Scholz’s government scrambled to find new fuel sources while pushing ­renewables.

China, in the meantime, ­pivoted from buying German vehicles to undercutting them with cheaper models, particularly in the EV sector.

At a recent televised debate Merz, who left politics for business for 12 years after losing a power struggle with Merkel, accused Scholz’s government of economic “incompetence” after two years of recession. Scholz shot back: “I didn’t invade Ukraine!”

Scholz’s coalition finally ­collapsed in November – within hours of Trump winning the US election – over a still unresolved conundrum around the strict “debt brake” that keeps ­federal government annual ­borrowing to 0.35% of GDP. The implosion ­triggered a general ­election seven months ahead of schedule.

But Scholz’s era of political turmoil might soon look like halcyon days.

Germany’s true Zeitenwende is still to come, argues veteran political ­analyst Herfried Münkler, as Berlin faces up to the painful realisation that the postwar order that welcomed the country back into the community of nations after the Nazi atrocities has come to an end.

“The biggest loser of the latest developments is Germany, not only because its economic power has shrunk but also because German poli­ticians relied unconditionally to the end on the transatlantic relationship,” he wrote in the newspaper Die Zeit.

“The next government will have to take great pains to reassert German leadership in Europe.”

Reforming the debt brake will be essential to that process, said Sascha Huber, a political scientist at the University of Mainz, as more defence ­spending will have to be financed with new debt. “But the first challenge will be ­forming a stable coalition,” he said.

Because he is unlikely to win a majority, Merz has said he aims to build a new ­governing ­alliance by Easter, setting up long weeks of tense negotiations in which Germany will be focused inward. His most likely partner will be Scholz’s Social Democrats but he may need yet another party to make the maths add up – a recipe for further volatility, Münch said.

Meanwhile, surveys suggest the anti-immigration, anti-Islam AfD will double support from the last ­election, to win about 20% of the vote. It has been polling in second place to Merz’s CDU-CSU bloc for more than a year. It calls for mass ­deportation of migrants, a resumption of Russian gas imports, an end to military aid for Ukraine and exiting the eurozone.

During the election campaign there has been a series of attacks in which the suspect is from a migrant background, which some analysts believe could boost AfD support. The latest came on Friday, when a Spanish tourist was stabbed at Berlin’s Holocaust memorial. Prosecutors saidon Saturday that the suspect was a 19-year-old Syrian refugee who appeared to have planned to kill Jews.

Although most analysts expect Merz to maintain the “firewall” ­barring formal cooperation with the far right, a strong AfD finish would greatly complicate his efforts to produce a reliable majority.

“I think it will be essential to a centrist coalition for him to make clear that he won’t accept support from the AfD again,” Huber said, referring to a taboo-busting move by Merz last month to solicit far-right votes in parliament for hardline migration proposals. “Otherwise it won’t work. Tthe AfD will always be trying to drive a wedge between the coalition parties.”

Germany has long been considered among the most politically stable of the world’s big democracies, only triggering snap elections roughly every two decades. But that pace could accelerate if the political fringes grow in influence, Huber said.

That sense of looming turbulence, with the AfD waiting in the wings, has troubled many voters, drawing hundreds of thousands on to the streets in recent weeks in defence of democracy.

At a recent protest co-organised by senior activists Grannies Against the Right (Omas Gegen Rechts) in the eastern town of Teltow, 70-year-old retired history teacher Sabine Ludwig said she saw “scary” echoes of the Weimar era, a century ago.

“There won’t be endless chances for the democratic centrist parties to come together and keep the AfD out,” she said. “I hope they seize it.”