“Germany hasn’t had an attack like this that’s killed a lot of people in a long time, so clearly there will be pressure on her,” Hamilton said by phone. “But there will also be a sense that Europeans are in this together, that it’s a common threat.”

For Merkel, Monday’s tally of dead and injured may be a day of reckoning for her political future. Her hopes of winning a fourth term in federal elections next fall may not survive another public debate about the risks of terrorism and anxieties over an influx of over a million refugees since the beginning of 2015.

“Our worst fears are confirmed,” Stephan Meyer, a Bavarian lawmaker in the lower house allied with Merkel, told Bild newspaper.

Beleaguered by a wave of anti-establishment sentiment in reaction to the refugee crisis, Merkel had appeared to weather the challenge, regaining some of the voter support lost to remain the favourite to win the 2017 election. Yet she has remained vulnerable, with any potential terror attack among the factors cited as able to pollute the political climate.

The attack on a festive pre-Christmas crowd in the German capital came hours after Russia’s ambassador to Turkey was gunned down in Ankara and a shooting at an Islamic center in Zurich unleashed a manhunt. While Berlin’s experiences compounded the sense of unease across the region, it also served to underscore that it wasn’t alone.

“An attack can go one of two ways,” Holger Schmieding, chief economist at Berenberg Bank, said in a phone interview. “On the one hand it could lead in times of external dangers to people pulling together - on the other it can also fan the extremists.”

Schmieding compared the probable assault to large-scale attacks in France since the beginning of 2015, in which more than 200 people were killed. In Nice on July 14, a truck ploughed through a crowd on the city’s waterfront, killing 86.

Merkel’s image as a pillar of stability was tested in July when a spate of attacks, including a suicide bomber at a beer festival and an axe-wielding attacker on a commuter train - both asylum seekers - shook public opinion and renewed the debate on safety.

Merkel in those cases vowed swift action against those who commit terrorism. Within her Christian Democratic Union, Merkel has toughened her stance on deportation of refugees who don’t qualify for asylum. At a party conference this month, she joined conservatives in calling for a ban on full-face veils where legally possible.

Looming on the party’s right flank is the AfD, which has swept into 10 state parliaments since its inception in 2013, including a string of electoral breakthroughs this year. The party’s rise has been accompanied by street rallies, particularly in the formerly communist east, that have featured slogans denouncing Islamist extremism.

“Your guess would have to be it’s yet another extremist Islam attack, that’s going to continue to weaken Merkel, that’s going to continue to support the populists,” Ian Bremmer, president of New York-based political risk consultancy Eurasia Group, said on Bloomberg TV.

For the chancellor, the daughter of a Lutheran pastor, Monday night’s deaths at a Berlin Christmas market are shocking, but the incident is not something that will catch her by surprise, according to Julianne Smith, senior fellow and director, Strategy and Statecraft Program at the Centre for a New American Security.

Merkel is “going to take hits on multiple sides,“ Smith said in an interview. “Some will accuse her of going too far and some will say she hasn’t done enough.”