BERLIN — The deadly truck rampage at a Christmas market in Berlin has opened up a political minefield for Chancellor Angela Merkel.

On a chaotic day of grief and uncertainty, after 12 people were killed and dozens injured on Monday, leaders of the country’s rising far-right Alternative for Germany party assailed the Chancellor in blunt, visceral terms, describing the victims as “Merkel’s dead”.

The attack, which saw a driver steer a speeding tractor-trailer through crowds of shoppers at a popular Christmas market in central Berlin, is already reshaping what promises to be a tumultuous European political year in 2017.

Ms Merkel is the most powerful defender of the reeling European Union, yet such a bloody terror attack on German soil is certain to complicate her campaign for a fourth term in office. The prospect that she could be weakened, or voted out, would be potentially devastating for the bloc.

The German fight against terrorism, which has proved to be uneven, is not helping her. It was only two months ago that authorities in the state of Saxony failed to catch a dangerous suspect who was preparing bombs in his apartment and arrested him only after three plucky Syrians caught the man, who then committed suicide in custody.

Public confidence in the Chancellor first dipped when authorities largely lost control of the influx of refugees in the summer of last year. Ever since, there has been a clear correlation between her personal ratings and voters’ fear of terrorist attacks.

Ms Merkel’s campaign for the 2017 election is set to focus on “security” and “no experiments”. And both these slogans will be undermined by the truck attack. She will now hope that mainstream Germans will do as they normally would: Rally behind whichever government they have and remain as calm as they did, for instance, when they were struck in 2009 by the harshest economic downturn since the second World War.

While the attack is unlikely to result in Ms Merkel having to quit her post, in the short term, she may have no option but to give in to calls for tougher security policies. She can be expected to push for faster processing of asylum seekers and for more extraditions of those who are not acknowledged as refugees.

Beyond politics, the assault made plain that Germany, like France and Belgium, is now a primary European target for mass terror attacks.

The attack came at a precarious moment in Germany, amid concerns about Russia meddling in domestic politics and a still-angry populist backlash against Ms Merkel over her decision to open the German border to nearly one million migrants and refugees in 2015.

In Berlin, several hundred people attended an emotional service held between the wooden stalls of the Christmas market, located beside the Kaiser Wilhelm Memorial Church, a symbolic site whose spire, jagged from bomb damage, was intentionally left unrepaired after World War Two. Among those who came were a group of 60 to 70 members of a local mosque.

“We wanted to show our solidarity,” said a member of the group, Hasnen Ahmad , “and that our community stands for peace.”

The arrest of a Pakistani suspect came after a witness told the police that he had seen a suspect jump from the truck. The witness tried to follow him through a nearby park to where he was arrested.

Political opponents of Ms Merkel quickly seized on his status as an asylum seeker to renew their criticism that her migration policies had made Germany vulnerable to terrorism — before the man was cleared of suspicion.

“Germany is no longer safe,” said Ms Frauke Petry, the leader of the Alternative for Germany party. Noting the successive terrorist attacks in France, including the Nice attack in July, Ms Petry called the carnage at the Berlin market “not just an attack on our freedom and our way of life, but also on our Christian tradition”.

Ms Daniela Schwarzer, the leader of the German Council on Foreign Relations, said the harsh reaction offered a taste of the bitter debate to come in 2017. “They were very quick to link this directly to Merkel, and they said horrific things, blaming her for the deaths,” said Ms Schwarzer. “That gives us a sense of what is coming in the electoral campaign.” AGENCIES