A senior member of the right-wing Alternative for Germany (AfD) mounted an attack on Angela Merkel, calling to remove her from office "in a straightjacket," at a time when the Chancellor is increasingly pressed for her open door refugee policy.

Björn Höcke, the chairman of AfD in Thuringia, made the remarks during a party rally, which saw approximately 2,400 people gather in the regional capital of Erfurt on Wednesday. Five-hundred activists held a counterdemonstration, Germany's weekly news magazine Focus reported.

Germany is "ruled by idiots," he added, referring to Merkel's management of the refugee crisis. According to official data, approximately 1.1 million asylum seekers entered the country in 2015 alone. This is a record number for Germany, home to 81 million people, or any other European nation.

© AP Photo / dpa,Hendrik Schmidt Bjoern Hoecke

A day before the rally, the public prosecutor's office in the city of Halle launched an investigation into Höcke on charges of sedition following his speech at a rally in Saxony-Anhalt, the media outlet noted.

The debate on migrants and Merkel's open door policy has been a major test for the government, the ruling party and the country's political leadership. It has been overshadowed by mass sexual assaults and robberies, which took place in Cologne during New Year celebrations. The attacks, which shocked the nation, are largely blamed on migrants from the Middle East and North Africa.

Not surprisingly, the tough stance on immigration has so far paid off in terms of poll standings for Eurosceptic and right-wing parties. A survey, published on Monday, shows that AfD would receive 11.5 percent of the vote if parliamentary elections were held today in what is the best result for the party in its history.

Wir etablieren uns als drittstärkste Kraft im Land https://t.co/BjfobAYRIt* Wir sind bereit f.d.Rettung Deutschlands pic.twitter.com/2DKviu7Sil — Frauke Petry (@FraukePetry) 12 января 2016

​The party would have taken third place. Merkel's Christian Democratic Union of Germany (CDU) and its sister party in Bavaria, the Christian Social Union (CSU), received 35 percent. The Social Democrats (SPD) took 21.5 percent.