BERLIN — As flags on government buildings across Germany hang at half-mast in homage to the victims of Berlin's Christmas market attack, Angela Merkel's opponents aren't waiting to capitalize on the tragedy to weaken the 62-year-old chancellor's 2017 re-election campaign.

With the perpetrator apparently still on the run, after police released the Pakistani asylum-seeker they arrested immediately after the attack that killed 12 people and injured 48, Merkel already faces accusations that her refugee policy put Germany in mortal danger.

“We must not be under any illusion. The environment for such deeds was imported negligently and systematically throughout the last year and a half,” said Frauke Petry, leader of the far-right party Alternative für Deutschland (AfD).

By leveraging public anger at Merkel's decision in autumn 2015 to grant safe passage to refugees stranded in Hungary, the AfD has seen its support in opinion polls rise from 4 percent in August 2015 to around 12 percent now. Following success in regional elections — it overtook Merkel’s conservatives in Mecklenburg-Vorpommern state in September — the anti-immigrant party is likely to enter the Bundestag, parliament's lower house, in the fall.

Shortly before Monday's attack in Berlin, German news agency DPA reported that the AfD leadership had chosen a campaign strategy that would focus on the concerns of ordinary people via what an internal document described as “carefully planned provocations.” It hopes to trigger nervous reactions from its rivals, and the more they try to stigmatize the party, ”the more positive this will prove for the party’s profile,” the DPA report quoted the document.

'Heavy artillery'

In retrospect, it sounds like the blueprint for the reaction of Marcus Pretzell, the AfD’s candidate in next year’s regional election in the state of North Rhine-Westphalia, to Monday's attack. Moments after the news broke, he tweeted: “These are Merkel’s dead.”

Ralf Stegner, deputy leader of the Social Democrats (SPD), responded by accusing Pretzell and his party of attempting to capitalize politically on the attack. It was a “disgusting political exploitation of this tragedy" when everyone should be showing "respect for the victims,” he wrote on Twitter.

The fact that it was the SPD — currently Merkel's coalition allies, but which will challenge her for the chancellorship next year — that defended the chancellor is symptomatic of the problem she was already going to face in the campaign: Her welcoming attitude to the refugees won her new admirers among German center-left supporters but alienated her from some in the conservative wing of her own Christian Democrats (CDU) and the allied Bavarian Christian Social Union (CSU).

“We owe it to the victims, those who were affected [by the attack] and the entire population that we should now think over and adjust our entire migration and security policy,” said Bavarian state premier and CSU leader Horst Seehofer on Tuesday morning, adding that he would discuss with the Bavarian state government the “possible implications and suggestions for [Merkel’s] federal government.”

Teflon Angie

So far, Seehofer's repeated criticism of Merkel's refugee policy have failed to make a lasting dent in her popularity. Now in her third term, her personal approval ratings are close to 60 percent despite waves of outrage to refugee-related events such the mass sexual assaults on women in Cologne on New Year's Eve 2015, or the rape and murder of a college student in Freiburg in October, for which an Afghan asylum seeker was arrested.

Demonstrating her refusal to adopt the tone and language of the AfD to neutralize them as a political threat, Merkel told German TV earlier this month that if the Freiburg attacker turns out to be an Afghan refugee, he should be condemned "just like with any other murderer ... But that shouldn’t be combined with a rejection of an entire group."

Tackling the same issue head-on at her first statement in response to Monday's atrocity, the chancellor — dressed in black — said: “We must assume at the current time that it was a terrorist attack.” She added: “I know that it would be particularly difficult for all of us to bear if it is confirmed that this deed was carried out by a person who sought protection and asylum in Germany.”

Sure enough, shortly afterwards German Interior Minister Thomas de Maizière said the man arrested on suspicion of carrying out Monday's attack was a 23-year-old Pakistani who had applied for asylum in Germany. In a detail that could potentially be embarrassing for German authorities, the minister said immigration authorities had not been able to question the man about his asylum request because there was nobody who could provide interpretation into German from the man's language, Balochi.

A few hours later, after media reports that German police believed they may have arrested the wrong man, federal prosecutor Peter Frank said police didn't know for sure whether the man in police custody really was responsible, and that investigators should "get used to the idea that the suspect possibly isn't the criminal or doesn't belong to the criminal group." Later in the day, authorities said the Pakistani man had been released.

Such confusion is likely to increase the pressure on Merkel to toughen up security measures. A taste of things to come came from the interior minister for the state of Saarland, the CDU's Klaus Bouillon, who said in a radio interview that Berlin was in a state of war “even though some people, who always only want to see the good, don’t want to see this.” From now on, he said, police should use “heavy artillery” if necessary.

Hortense Goulard contributed reporting.