All of which has sparked questions about the source of the pent-up anger, particularly since the explosively divisive issue of 2015’s mass refugee arrivals had seemingly faded as the influx eased last year.

“The rage is not fuelled only by Merkel’s refugee policy, but also by powerlessness, from the feeling of not being taken seriously by ‘them up there’,” the weekly magazine Spiegel said.

Timo Lochocki, a political analyst at the German Marshall Fund, said the anger had been “long in the making” because the ruling coalition of Merkel’s “CDU and the Social Democratic Party do next to nothing to appease these voters”.

“Over the last three to four years, the anti-establishment voters, plus disillusioned conservatives fed up with the euro zone rescue and migration deal, are shifting more and more to the right,” he said – and straight into the arms of the AfD.

Far from being a spontaneous outpouring of fury, the protests are highly organised – and have the AfD’s fingerprints all over them.

Many of the so-called enraged citizens (“Wutbuerger” in German) arrive with AfD posters, reflecting the party’s success in tapping into the outrage over the arrival of more than 1 million refugees to Germany since 2015.

Ahead of Merkel’s planned rally on Saturday at her constituency’s Baltic Sea resort of Binz, a call went out on social media among self-styled “patriots” to mobilise for a protest.

Rene Springer, an adviser to AfD candidate Alexander Gauland, told Die Zeit weekly that it was “compulsory for AfD members to go to events of government politicians” and show their disapproval of the establishment’s programme. But there is also a second motive – to gain media attention.

“Friends of the party say, if the media is not reporting about us, then we should go and protest loudly, so that people will report about us,” Springer said.

AfD, whose leading politicians have come under fire for making racist comments, is expected to win seats in the German parliament for the first time. With opinion polls putting its support at between 8 and 12 per cent, the group could well become the country’s third-largest party.

Nico Siegel, who heads the Infratest Dimap polling institute, described the AfD as a “vacuum cleaner of the unsatisfied”.

With mainstream parties all shunning the AfD, its supporters have been particularly vocal because they feel it is their only way to be heard.

“The angry voters feel disempowered as they know that even if they voted for the other smaller parties, they won’t get rid of Merkel,” said Lochocki, of the German Marshall Fund. “This is basically why people flock to the AfD, and why they take to the streets.”

Sigmar Gabriel, the SPD politician who is also foreign minister, said Merkel herself was to blame for the AfD’s popularity, since her party had failed to “show concern to those who have the feeling that they have been forgotten”.

But the Frankfurter Allgemeine Zeitung said it was Merkel’s strategy of avoiding taking a stance on contentious issues that has backfired as voters feel increasing frustrated about her vague positions.

“The chancellor has become an object of polarisation even though her political style is exactly the opposite,” the newspaper said.

Merkel has vowed to press on with her rallies, even if she has said that “people who whistle and shout no longer have any interest in listening”.

“But what one must never forget is that at these rallies, there is always a majority of people who are listening and who want to be democratically informed,” she told the Berliner Zeitung. “I think it is important for me to visit not only comfortable places.

“It is important to give people, who want to listen and form their own opinion, the possibility to do so. And every event is also an encouragement to those who stand up against hate.”