In a stunning development for German politics, Germany’s anti-immigrant, nationalist party Alternative for Germany, or AfD, has taken the lead in the east of the country ahead of Chancellor Angela Merkel’s Christian Democrats (CDU), just a month before regional elections in the eastern states of Saxony and Brandenburg, an opinion poll showed on Sunday.

The AfD is currently polling at 23%, ahead of Angela Merkel’s Christian Democratic Union, or CDU, which is at 22%, according to a poll carried out by Bild. The far-left Die Linke is in third place at 14% while the Greens are at 13% and the center-left Social Democrats (SPD) on 11%.

The eastern states of Brandenburg and Saxony hold regional elections on Sept. 1, followed by Thuringia a month later.

As shown in the map below, the AfD has taken a leadership position in Germany's formerly communist, and more economically backward eastern states. The good news for Europe's establishment is that in the west of the country, the AfD remains further back, and last polled in fourth position at 12%, with the CDU at 27%, the Greens 25% and SPD 13% in the Kantar Emnid poll of 1,419 conducted from July 25-31.

The AfD barged on the scene in 2017, when it entered Germany’s national parliament for the first time as the third largest party, helped by voter anger at Merkel’s decision to welcome asylum seekers from the Middle East and Africa.

As Reuters notes, an inevitable defeat for the SPD in Brandenburg, where it has won all of the last six elections there since German reunification in 1990, and the CDU in Saxony would put more pressure on the coalition partners to rethink their alliance in national government, while further derailing the German political establishment.

As Bloomberg adds, the former communist east that saw massive right-wing protests last year is now back in focus as voters in three states go to the polls this fall. In Saxony and Brandenburg, Merkel’s Christian Democrats and their junior partner, the Social Democrats, are set to lose for the first time since reunification in 1990 to the upstart AfD.

That could not only implode her fragile coalition but upend a political landscape dominated by two parties since World War II.

While the AfD looks set to sweep in the East, it still has a ways to go at the national level, with the poll showing the AfD up one percentage point at 14%, the SPD down a point at just 13%, the CDU steady at 26%, the Greens on 23%, the Free Democrats on 9% and the Linke on 8%.