The first far-right party to enter Germany's parliament in more than half a century has been likened by the country's foreign minister to the Nazis.
Founded in 2013 as an anti-euro party, the Alternative for Germany (AfD) has turned its focus to immigration and Islam.
It's on track to take 13 percent of the vote in the federal election that returned Chancellor Angela Merkel for a fourth term.
The far-right has not been represented in the Bundestag since the 1950s - a reflection of Germany's efforts to distance itself from the horrors of the Holocaust. After the AfD's strong election showing, hundreds of demonstrators took to the streets of Berlin, Hamburg and Cologne in protest.
The party already has MPs in 13 of Germany's 16 state parliaments, and last year AfD pushed Mrs Merkel's ruling conservatives into third place in a regional election.
What does AfD stand for?
Campaigning against mass immigration
AfD has capitalised on a nationalist backlash against Chancellor Merkel's welcome for almost 900,000 migrants and refugees in 2015.
When the numbers of migrants arriving in Germany surged in 2014-2015, AfD made that the focus of its party platform.
There were contacts with the anti-immigration Pegida movement, which staged weekly marches against what it called "the Islamisation of the West".
AfD also adopted some of Pegida's anti-establishment rhetoric, for example the slogan "Lügenpresse" ("lying press"), which has echoes of the Nazi era.
AfD is particularly strong in parts of ex-communist eastern Germany - yet the biggest concentrations of immigrants are not in those areas.
It wants Germany to reintroduce permanent border controls and says the EU's external borders must be "completely shut". That position contradicts Schengen - the EU's free movement zone, covering most of Europe, where border checks are generally minimal.
AfD argues that Germany must set up a new border police force. Frauke Petry, who stepped aside from the AfD leadership earlier this year, even said German police should "if necessary" shoot at migrants seeking to enter the country illegally.
Challenging Islam as 'not German'
In May 2016, AfD adopted an explicitly anti-Islam policy. Its election manifesto has a section explaining why it believes "Islam does not belong to Germany".
AfD would ban foreign funding of mosques in Germany, ban the burka - the full-body veil - and the Muslim call to prayer, and put all imams through a state vetting procedure.
"Moderate" Muslims who accept integration are "valued members of society", the programme says. But it argues that multiculturalism does not work.
Just days before the election, one of AfD's lead candidates, Alexander Gauland, stirred controversy by saying the government's top integration official, Aydan Özoguz, could be "disposed of in Anatolia". Ms Özoguz is a German of Turkish origin.
Mr Gauland also drew criticism for declaring that Germans should be "proud" of their soldiers in both world wars. While SS units were notorious for German atrocities in WWII, the regular armed forces also committed many war crimes.
Earlier another top AfD politician, Björn Höcke, caused outrage by condemning the Holocaust memorial in Berlin.
Against the euro
AfD's launch in early 2013 was all about challenging the eurozone bailouts and rejecting the EU's arguments for keeping the euro.
It still promises to abandon the euro and reintroduce the Deutschmark.
Its anti-euro policy echoes the Euroscepticism of other right-wing parties in Europe, especially the French National Front (FN), the UK Independence Party (UKIP) and Austria's Freedom Party (FPOe).
More powers must return to the nation states, AfD says, opposing all "centralising" moves in the EU, and anything that smacks of Euro-federalism.
If the EU fails to reform and continues centralising, AfD says, the party will seek to pull Germany out of the EU.