German Chancellor Olaf Scholz called the results of two regional elections that saw big wins for the far-right AfD and losses for his coalition "bitter" and urged mainstream parties to form governments without "right-wing extremists".
The Alternative for Germany (AfD) became the first far-right party to win a state legislature election in Germany since World War II with its result in weekend voting in Thuringia. It came a close second behind the conservatives in Saxony, projections late on Sunday showed.
But the AfD, deemed "right-wing extremist" by security officials in both of the east German states, is unlikely to be able to govern as other parties have so far refused to collaborate with it to form a majority.
Still, the nationalist, anti-migration and Russia-friendly party could end up with enough seats in both states to block decisions requiring a two-thirds majority such as the appointment of judges or top security officials, giving it unprecedented power.
"The results for the AfD in Saxony and Thuringia are worrying," Scholz said in a statement to Reuters. He clarified he was talking as a lawmaker for his centre-left Social Democrats (SPD).
"Our country cannot and must not get used to this. The AfD is damaging Germany. It is weakening the economy, dividing society and ruining our country's reputation."
With a year to go until Germany's national election, the results on Sunday punished Scholz's fractious coalition, which could aggravate infighting.
All three ruling parties lost votes, with only his SPD comfortably clearing the five per cent threshold needed to stay in the two states' parliaments.
Populist leftist newcomer, the Sahra Wagenknecht Alliance (BSW), founded by a former member of the East German Communist Party, did better than all of three coalition partners in its first state elections, coming in third place.

Death toll from Venezuela quakes rises to 3,535 as thousands remain displaced
Russian strikes kill 26, exposing Ukraine air-defence shortages
Clashes escalate at Sri Lanka prison to leave 25 dead, many more injured
Six killed in India's Mumbai as rains wreak havoc, disrupt travel
Wildfire in southern France forces 10,000 people from their homes
Folarin Balogun to play for US after FIFA suspends red-card ban
Arab League condemns Israeli demolition of entire neighborhood in Lebanon
Eight killed in landslides at Rohingya refugee camps in Bangladesh
