The German Parliament is to vote Thursday on whether to label the killings of Armenians by Ottoman Turks a century ago as genocide, a move that Turkey's prime minister said would "test" the two countries' relations at a sensitive time.
The motion, which is backed by Chancellor Angela Merkel's conservative bloc, their partners in the government, the Social Democrats, and the opposition Greens, looks set to pass with wide support.
Turkey's Prime Minister Binali Yildirim said this week his country would not nix a deal with the European Union on curbing the flow of migrants to Europe over the motion, but told party officials in Ankara Thursday that the vote was a "true test of friendship."
Historians estimate that up to 1.5 million Armenians were killed by Ottoman Turks around the time of World War I, an event viewed by many scholars as the 20th century's first genocide.
Turkey denies that the killings that started in 1915 were genocide and contends the dead were victims of civil war and unrest. Ankara also insists the death toll has been inflated.
When other countries have called the killings genocide it has led to diplomatic strife with Turkey, but not lasting damage.
Last year, for example, Turkey temporarily recalled its ambassadors to Vienna and the Vatican after Austria and Pope Francis described the killings as genocide.
The German motion says that the Armenians' fate "is exemplary for the history of mass destruction, ethnic cleansing, expulsions and genocides which marks the 20th century in such a terrible way."
That echoes the words German President Joachim Gauck used in a speech in April last year. His comments marked a shift in Germany's stance after officials previously avoided the term.
The government backed his formulation at the time. Turkey was irked by Gauck's words last year, but there were no serious consequences for German-Turkish relations.
The new motion stresses that Germany is aware of the "uniqueness" of the Nazi Holocaust and it "regrets the inglorious role" of Germany, the Ottoman Turks' main military ally at the time of the Armenians' killings, of failing to stop the "crime against humanity."
It also urges the German government to "encourage" Turkey to "deal openly with the expulsions and massacres" in order to "lay the necessary foundation stone for a reconciliation with the Armenian people."
In February, as the EU prepared for a summit with Turkey, the Greens agreed to withdraw a motion on the killings in exchange for assurances from the governing parties that they would draw up a joint resolution. While it is symbolically significant, it has no legal effect.
Thursday's vote comes amid tension between Turkey and the European Union over the EU's conditions for granting visa-free entry for Turks. Speeding that up was one of the incentives for Turkey to accept a deal with the EU, championed by Merkel, on curbing migrant flows to Europe.
Yildirim on Thursday accused the German Parliament of using the vote to distract from unspecified domestic issues.
"At times countries that we consider to be friends come up with these bright ideas to distract attention when they fall into despair with their domestic policy," he said. "This is one of them."
Merkel spokeswoman Christiane Wirtz made clear that the chancellor supports the motion. However, she and her deputy weren't expected to be in Parliament Thursday. Officials cited scheduling reasons, while the foreign minister was on a long-planned trip to Latin America.