German Chancellor Angela Merkel commemorating the 100th anniversary of the World War I battle of Verdun | Sean Gallup/Getty Images Bundestag urges Angela Merkel to stand up to Turkey Ankara is readying an ‘action plan’ in response to Germany’s Armenian genocide resolution.

BERLIN — As Angela Merkel tries to salvage the EU's refugee deal with Turkey, German MPs want her to stand up to President Recep Tayyip Erdoğan and other Turkish officials for their angry and aggressive response to a vote on the Armenian genocide.

The chancellor was accused of being mealy-mouthed in her response to verbal attacks by Erdoğan and others on German MPs of Turkish origin for their role in the Bundestag's (lower house) approval of a resolution declaring the massacre of hundreds of thousands of Armenian Christians under Ottoman rule an act of genocide.

"Their blood is impure and we know whose mouthpiece they are," the Turkish president said in Istanbul on Sunday, singling out 11 German MPs of Turkish descent. They were "the long arm of the separatist terrorists placed in Germany," he said.

Furious at last week's vote, Ankara withdrew its ambassador to Berlin, leaving Merkel struggling to ring-fence a deal for Turkey to help Europe with its refugee crisis in return for visa liberalization for Turks. Relations were already strained after a German comedian read out an obscene poem about Erdoğan on TV. Under pressure, Germany agreed to prosecute him.

Turkey opposes the term "genocide" being attached to the deportation and murder of members of the Christian Armenian authority by Ottoman Empire authorities during World War I, when Turkey was a German ally. While acknowledging there were deaths and deportations, Turkey rejects as exaggerated estimates that 800,000-1.5 million people died between 1915-16.

Last weekend, Ankara's Mayor İbrahim Melih Gökçek tweeted a collage of photos of 11 German-Turkish members of the Bundestag who backed the genocide resolution, accusing them of "stabbing us in the back."

Merkel's response, during a news conference Tuesday, was to call the Turkish response "incomprehensible" and defend the MPs in question as "freely elected parliamentarians.”

This fell far short of how the opposition Greens expected the chancellor to defend their German-Turkish co-chair Cem Özdemir, whose home has been put under increased police protection since the vote.

“The chancellor has to take up a definite position [against Erdogan,]” his Green colleague Claudia Roth, who is a vice-president of the Bundestag, told DPA news agency. “We can’t let him get away with that.”

Already in the lead-up to last Thursday's vote, Özdemir said he had received insults calling him “a traitor, Armenian pig, son of a whore, Armenian terrorist, or even a Nazi.”

“People — which includes, unfortunately, prominent people — are consciously stirring up hatred,” the Green MP, who had been a driving force behind the Armenian resolution, told journalists on Monday.

Conservative MP Michael Grosse-Brömer, a parliamentary leader of Merkel's conservatives, urged members of the Bundestag to "stand by one another" and reject any attempt at undue influence, saying it was "completely unacceptable to threaten MPs of Turkish descent based on how they vote.”

Thomas Oppermann, leader of the Social Democrat bloc — Merkel's partners in the ruling 'grand coalition' — said he hoped the chancellor would make it very clear "that she finds this witch-hunt against German parliamentarians intolerable.” The opposition Left party requested a special debate on the issue, which will take place on Thursday.

So far, however, the German protests have been to no avail. Ibrahim Kalin, a spokesman for Erdoğan, said on Wednesday that Turkey was "preparing an action plan" against Germany over the Armenian vote, with the foreign ministry in charge of drawing up the specific measures to take.

On Tuesday, the mayor of the Pazar district, which is home to members of Cem Özdemir’s family, told Turkish journalists he planned to withdraw Özdemir's honorary citizenship of the town. Instead, the title will be offered to the only German MP to vote against the Armenian genocide resolution, the conservative backbencher Bettina Kudla.

Also on Tuesday, a scheduled German media visit to a Turkish air base in Incirlik, where German fighter jets are stationed to praticipate in the international campaign against ISIL, was cancelled at the last-minute by Turkish authorities.

The Turkish government had hoped that its lobbying and influence among the 2.9 million German citizens of Turkish ancestry — who make up about 4 percent of the entire population — would prevent the repeatedly postponed Armenian vote.

“I believe many of the attacks are meant to stir up the Turkish community in Germany, and to increasingly set them against the rest of the German population,” Hans-Georg Fleck from the Istanbul bureau of the Friedrich Naumann Foundation, a German Liberal think-tank, told Deutschlandfunk radio on Wednesday, adding that a "considerable share of Turks in Germany, at least among those who can still vote in Turkey, is particularly receptive to Mr. Erdoğan's arguments and propaganda."

As of Wednesday afternoon, the Turkish ambassador to Germany was still out of the country, according to an embassy spokesman. The government in Berlin was sticking to a softer diplomatic approach: The German foreign ministry said Tuesday it had "invited" a representative of the embassy to discuss recent developments.